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United States Patent |
5,518,864
|
Oba
,   et al.
|
May 21, 1996
|
Method of forming polyimide film pattern
Abstract
Disclosed is a photosensitive resin composition, containing a polyamic acid
derivative having a repeating unit represented by general formula (1)
given below and a photosensitive agent:
##STR1##
where, R.sup.1 represents a tetravalent organic group, R.sup.2 represents
a divalent organic group, and R.sup.3 and R.sup.4 represent a monovalent
organic group, at least one of R.sup.3 and R.sup.4 being an organic group
having at least on hydroxyl group bonded to an aromatic ring. A
semiconductor substrate is coated with the photosensitive resin
composition, followed by exposing the coated film to light through a
patterning mask and subsequently applying a development and a heat
treatment so as to form a polyimide film pattern. A baking treatment also
be applied immediately after the exposure step. The photosensitive resin
composition of the present invention performs the function of a positive
or negative photoresist film and the function of a polyimide protective
film on a semiconductor substrate.
Inventors:
|
Oba; Masayuki (Yokohama, JP);
Hayase; Rumiko (Kawasaki, JP);
Kihara; Naoko (Matsudo, JP);
Hayase; Shuzi (Kawasaki, JP);
Mikogami; Yukihiro (Yokohama, JP);
Nakano; Yoshihiko (Tokyo, JP);
Oyasato; Naohiko (Kawaguchi, JP);
Matake; Shigeru (Yokohama, JP);
Takano; Kei (Yokohama, JP)
|
Assignee:
|
Kabushiki Kaisha Toshiba (Kawasaki, JP)
|
Appl. No.:
|
220058 |
Filed:
|
March 30, 1994 |
Foreign Application Priority Data
| Sep 28, 1990[JP] | 2-259032 |
| Jan 17, 1991[JP] | 3-3962 |
| Mar 06, 1991[JP] | 3-39854 |
| Mar 28, 1991[JP] | 3-90001 |
Current U.S. Class: |
430/325; 430/165; 430/167; 430/189; 430/192; 430/193; 430/197; 430/326; 430/330 |
Intern'l Class: |
G03F 007/38; G03F 007/023 |
Field of Search: |
430/165,192,193,167,189,191,197,330,325,326
528/353
525/436
|
References Cited
U.S. Patent Documents
5298359 | Mar., 1994 | Maeda et al. | 430/167.
|
5320935 | Jun., 1994 | Maeda et al. | 430/325.
|
Primary Examiner: Chu; John S. Y.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt
Parent Case Text
This is a division of application Ser. No. 07/766,334, filed on Sep. 27,
1991 now U.S. Pat. No. 5,348,835.
Claims
What is claimed is:
1. A method of forming a polyimide film pattern, comprising the steps of:
forming a resin layer on a substrate, said resin layer containing as a main
component at least one material selected from the group consisting of (a)
a photosensitive resin composition comprising a polyamic acid derivative
having a repeating unit represented by general formula (1) and a o-quinone
diazide compound, (b) a photosensitive resin composition comprising a
polyamic acid derivative having a repeating unit represented by general
formula (1), a polyamic acid having a repeating unit represented by
general formula (2), and a o-quinone diazide compound, and (c) a
photosensitive resin composition comprising a polyamic acid derivative
having a copolymer structure including a repeating units represented by
general formula (1) and a repeating unit represented by general formula
(2) and a o-quinone diazide compound,
##STR140##
where, R.sup.1 represents a tetravalent organic group, R.sup.2 represents
a divalent organic group, R.sup.3 and R.sup.4 represent a monovalent
organic group or hydroxyl group, at least one of R.sup.3 and R.sup.4 being
an organic group having at least one hydroxyl group bonded to an aromatic
ring, R.sup.5 represents a tetravalent organic group, and R.sup.6
represents a divalent organic group;
selectively exposing a predetermined region of the resin layer to light;
developing the resin layer after the light exposure so as to selectively
remove or leave unremoved said predetermined region of the resin layer;
and
heating the developed resin layer so as to imidize the resin layer.
2. The method of forming a polyimide film pattern according to claim 1,
further comprising the step of forming a thin film of a polyamic acid on
the substrate before the step of forming a resin layer containing as a
main component at least one material selected from the group consisting of
photosensitive resin compositions (a), (b) and (c).
3. The method of forming a polyimide film pattern according to claim 1,
wherein a baking treatment is applied at 90.degree. to 200.degree. C. to
the resin layer after the light exposure step, followed by developing the
resin layer.
4. A method of forming a polyimide film pattern, comprising the steps of:
forming on a substrate a resin layer containing as main components a
polyamic acid having a repeating unit represented by general formula (2)
and a naphthoquinone diazide compound;
##STR141##
where, R.sup.5 represents a tetravalent organic group, and R.sup.6
represents a divalent organic group;
selectively exposing a predetermined region of the resin layer to light;
applying a baking treatment at 130.degree. to 200.degree. C. to the resin
layer after the light exposure;
developing the resin layer after the baking treatment so as to selectively
remove or leave unremoved the predetermined region of the resin layer; and
heating the developed resin layer to imidize the resin layer.
5. The method of forming a polyimide film pattern according to claim 4,
wherein said naphthoquinone diazide compound contained in the resin layer
is 1,2-naphthoquinone diazide-4-sulfonic acid ester.
6. The method of forming a polyimide film pattern according to claim 1,
wherein
said resin layer contains, as a main component, a photosensitive resin
composition comprising a polyamic acid derivative having a repeating unit
represented by the general formula (1) and a o-quinone diazide compound;
and
the amount of the o-quinone diazide compound is 0.1 to 30 parts by weight
of the amount of the resin component.
7. The method of forming a polyimide film pattern according to claim 1,
wherein
said resin layer contains, as a main component, a photosensitive resin
composition comprising a polyamic acid derivative having a repeating unit
represented by the general formula (1), a polyamic acid having a repeating
unit represented by the general formula (2), and a o-quinone diazide
compound; and
the amount of the o-quinone diazide compound is 5 to 50 parts by weight of
the amount of the resin component.
8. The method of forming a polyimide film pattern according to claim 1,
wherein
said resin layer contains, as a main component, a photosensitive resin
composition comprising a polyamic acid derivative having a copolymer
structure including a repeating unit represented by the general formula
(1) and a repeating unit represented by the general formula (2) and a
o-quinone diazide compound; and
the amount of the o-quinone diazide compound is 0.1 to 30 parts by weight
of the amount of the resin component.
9. The method of forming a polyimide film pattern according to claim 5,
wherein said 1,2-naphthoquinone diazide-4-sulfonic acid ester is at least
one compound selected from the group consisting of
##STR142##
10. The method of forming a polyimide film pattern according to claim 9,
wherein a negative polyimide film pattern is obtained.
11. The method of forming a polyimide film pattern according to claim 5,
wherein said 1,2-naphthoquinone diazide-4-sulfonic acid ester is at least
one compound selected from the group consisting of
##STR143##
12. The method of forming a polyimide film pattern according to claim 11,
wherein a negative polyimide film pattern is obtained.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photosensitive resin composition for
forming a polyimide film pattern used as an insulating material of an
electronic part or as a passivation film, an .alpha.-ray shielding film or
an interlayer insulating film in a semiconductor device. The present
invention also relates to a method of forming the polyimide film pattern.
2. Description of the Prior Art
In a semiconductor device, a protective film (passivation film) is formed
on the surface of a semiconductor substrate having a semiconductor element
formed therein in order to protect the element from the influence of the
external environment and to improve the reliability of the element. In
general, a polyimide resin excellent in its electrical properties such as
the insulating properties and in its resistances to radiation and heat is
widely used as a material of the protective film. These excellent
properties also allow the polyimide resin to be used widely as a material
of the .alpha.-ray shielding film in a semiconductor device and as a
material of the interlayer insulating film included in a multilayer
interconnection structure.
A polyimide resin film can be easily formed from its precursor of a
polyamic acid. Specifically, a predetermined surface is coated first with
a varnish of the polyamic acid, followed by heating the coated layer so as
to form a film. Then, a heat treatment is applied to the film so as to
subject the polyamic acid to a cyclizing reaction. As a result, the
polyamic acid is cured (imidized) so as to form a polyimide film. In this
method, a stabilizing treatment can be performed at a relatively low
temperature and, thus, the method is employed widely.
On the other hand, a pad processing or the like is required in the
manufacture of a semiconductor device in order to make a through-hole in a
multilayered interconnection structure or to achieve an electric
connection to an external lead wire. Thus, it is necessary to pattern a
polyimide film formed as a protective film or an interlayer insulating
film in a semiconductor device so as to form a hole having a predetermined
pattern structure. In general, PEP (photo engraving process) using a photo
resist is employed for patterning a polyimide film. Specifically, a
polyimide film is formed first as described previously on the surface of a
semiconductor substrate having a semiconductor element formed therein,
followed by forming a photo resist film on the polyimide film. Then, the
photo resist film is selectively exposed to light and subsequently
developed so as to form a resist pattern. Further, the polyimide film
below the resist pattern is selectively etched using the resist pattern as
an etching-resistant mask so as to form a polyimide protective film or an
interlayer insulating film of a desired pattern.
In the conventional method of forming a polyimide film pattern described
above, however, it is necessary to perform formation of a polyimide film
and PEP for the pattern formation as two independent processes. Naturally,
the two-stage process makes the formation of the polyimide film pattern
troublesome.
To overcome the difficulty noted above, proposed is a resin composition
containing a precursor of a polyimide, said composition making it possible
to pattern a polyimide film without relying on PEP. For example, Published
Unexamined Japanese Patent Application No. 49-115541 discloses a polyamic
acid ester prepared by the reaction between a dichlorinated dicarboxyl
diester having a photopolymerizable group introduced therein by an ester
bond, which is used in place of the tetracarboxylic dianhydride which is
used generally, and a diamine. The polyamic acid ester exhibits a negative
photosensitivity. Specifically, when exposed to light, the exposed portion
of the composition itself is made insoluble in a developing solution. It
follows that patterning can be achieved simultaneously with formation of a
polyimide film. In other words, a polyimide film pattern can be formed
without relying on PEP.
However, very troublesome operations are required for synthesizing the
compound having a photopolymerizable group and for synthesizing the
polyamic acid ester. An additional difficulty is that chlorine ions are
contained as an impurity in the final product resin. Further, an organic
solvent is used as a developing solution, with the result that it is
necessary to use a large amount of the organic solvent in the
manufacturing process of the semiconductor device. This is not desirable
in terms of safety, sanitation and environmental contamination. What
should also be noted is that the formed polyimide film pattern is swollen
by the solvent, leading to a low resolution.
Published Examined Japanese Patent Application No. 59-52822 discloses a
heat resistant photosensitive material (or a negative photosensitive resin
composition) containing a compound having a carbon-to-carbon double bond
capable of dimerization or polymerization by actinic radiation and an
amino group. However, when the photosensitive material disclosed in this
prior art is used for forming a protective film in a resin-encapsulated
type semiconductor device or the like, the protective film is low in its
adhesion with a semiconductor substrate, a protective film of an inorganic
material on the substrate surface or with the encapsulating resin, with
the result that the reliability of the semiconductor device is impaired.
Further, it is necessary to use an organic solvent as a developing
solution in the developing step, as in the case of using the polyamic acid
ester referred to previously. It follows that various problems are brought
about, as pointed out previously.
Published Unexamined Japanese Patent Application No. 60-6365 discloses a
photosensitive resin composition containing a compound prepared by adding
as a salt an aminomethacrylate to the carboxyl group of a polyamic acid.
However, the photosensitive resin composition disclosed in this prior art
is defective in that the composition is low in solubility in a solvent
used.
On the other hand, Published Unexamined Japanese Patent Application No.
62-145240 discloses a photosensitive resin composition containing a
polymer having an isoimide structure. The composition exhibits a positive
photosensitivity. Specifically, when exposed to light, the exposed portion
of the composition is made soluble in a developing solution. However, the
polymer is low in its heat resistance and in sensitivity to light, making
it impractical to use the composition for forming a protective film
included in a semiconductor device.
A photosensitive resin composition exhibiting a positive photosensitivity
is also disclosed in Published Unexamined Japanese Patent Application No.
64-60630. Specifically, disclosed in this prior art is a composition
prepared by adding a photosensitive agent of o-quinone diazide compound to
an imide soluble in a solvent, said imide being synthesized by the
reaction between a diamine having a hydroxyl group bonded to the aromatic
ring and an acid anhydride. Further, Published Unexamined Japanese Patent
Application No. 62-135824 discloses a similar photosensitive resin
composition containing a quinone diazide as a photosensitive agent. Still
further, Published Unexamined Japanese Patent Application No. 60-37550
discloses a photosensitive precursor of the polyimide having an
o-nitrobenzyl ester group.
An alkaline aqueous solution can be used for the development of the
photosensitive resin composition of a positive photosensitivity.
Naturally, the problems brought about by the use of an organic solvent
need not be worried about. However, the construction of the polymer, which
is the main component of the resin composition, is restricted in the case
of the positive photosensitive resin composition, resulting in a low
adhesion with a silicon wafer, glass substrate, ceramic substrate,
encapsulating resin, metal, etc. which are widely used in a semiconductor
device.
In addition, Published Unexamined Japanese Patent Application No. 52-13315
discloses a positive photosensitive resin composition which can be
developed with an alkaline aqueous solution, i.e., a photosensitive
precursor of the polyimide which utilizes the solubility in an alkaline
solution of a polyamic acid and contains a naphtoquinone diazide compound
as a dissolution inhibitor. The photosensitive precursor of the polyimide
permits the pattern formation with a simplified process of film formation,
exposure and development. However, the difference in solubility in an
alkaline developing solution is not sufficiently large between the exposed
portion and the non-exposed portion in the developing step, making it
difficult to form a fine polyimide film pattern. Further, Published
Unexamined Japanese Patent Application No. 62-135824 referred to
previously teaches that a photosensitive polyimide precursor film is
heated to about 90.degree. C. before exposure to light so as to improve
the resolution of the formed polyimide film pattern. Even if the
particular process is applied, however, the resolution remains to be
insufficient in the case of using the photosensitive precursor of the
polyimide noted above.
SUMMARY OF THE INVENTION
An object of the present invention is to simplify the process of forming a
predetermined polyimide film pattern. To be more specific, the present
invention is intended to provide a photosensitive resin composition which
permits forming a polyimide film pattern without using a photoresist and a
method of forming a polyimide film pattern.
According to a first embodiment of the present invention, there is provided
a photosensitive resin composition for forming a polyimide film pattern,
comprising a polyamic acid derivative having a repeating unit represented
by general formula (1), and a photosensitive agent:
##STR2##
where, R.sup.1 represents a tetravalent organic group, R.sup.2 represents
a divalent organic group, and R.sup.3 and R.sup.4 represent a monovalent
organic group or hydroxyl group, at least one of R.sup.3 and R.sup.4 being
an organic group having at least one hydroxyl group bonded to an aromatic
ring.
According to a second embodiment of the present invention, there is
provided a photosensitive resin composition for forming a polyimide film
pattern, comprising a polyamic acid derivative having a repeating unit
represented by general formula (1), a polyamic acid having a repeating
unit represented by general formula (2), and a photosensitive agent:
##STR3##
where, R.sup.1 represents a tetravalent organic group, R.sup.2 represents
a divalent organic group, R.sup.3 and R.sup.4 represent a monovalent
organic group or hydroxyl group, at least one of R.sup.3 and R.sup.4 being
an organic group having at least one hydroxyl group bonded to an aromatic
ring, R.sup.5 represents a tetravalent organic group, and R.sup.6
represents a divalent organic group.
Further, according to a third embodiment of the present invention, there is
provided a photosensitive resin composition for forming a polyimide film
pattern, comprising a polyamic acid derivative having a copolymer
structure including a repeating unit represented by general formula (1)
and a repeating unit represented by general formula (2), and a
photosensitive agent:
##STR4##
where, R.sup.1 represents a tetravalent organic group, R.sup.2 represents
a divalent organic group, R.sup.3 and R.sup.4 represent a monovalent
organic group or hydroxyl group, at least one of R.sup.3 and R.sup.4 being
an organic group having at least one hydroxyl group bonded to an aromatic
ring, R.sup.5 represents a tetravalent organic group, and R.sup.6
represents a divalent organic group.
Still further, the present invention provides a method of forming a
polyimide film pattern, comprising the steps of:
forming on a substrate a resin layer containing as main components a
polyamic acid having a repeating unit represented by general formula (2)
and a naphtoquinone diazide compound:
##STR5##
where, R.sup.5 represents a tetravalent organic group, and R.sup.6
represents a divalent organic group,
selectively exposing a predetermined region of the resin layer to light;
applying a baking treatment at 130.degree. to 200.degree. C. to the resin
layer after the light exposure;
developing the resin layer after the baking treatment so as to selectively
remove or leave unremoved the predetermined region of the resin layer; and
heating the developed resin layer to imidize the resin layer.
Additional objects and advantages of the invention will be set forth in the
description which follows, and in part will be obvious from the
description, or may be learned by practice of the invention. The objects
and advantages of the invention may be realized and obtained by means of
the instrumentalities and combinations particularly pointed out in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawing, which is incorporated in and constitutes a part
of the specification, illustrates presently preferred embodiments of the
invention and, together with the general description given above and the
detailed description of the preferred embodiments given below, serves to
explain the principles of the invention.
FIG. 1 is a graph showing the sensitivity to light in the light exposure
step of a photosensitive resin composition according to the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the present invention, a substrate surface is coated first with a
photosensitive resin composition according to any one of the first to
third embodiments of the present invention, followed by exposing the resin
composition layer to light through a mask having a predetermined pattern
and subsequently applying a development so as to pattern the resin
composition layer. Finally, a heat treatment is applied to the patterned
composition layer so as to form a desired polyimide film pattern.
The photosensitive resin composition according to any one of the first to
third embodiments of the present invention comprises a resin component and
a photosensitive agent component. The resin component contained in the
photosensitive resin composition according to the first embodiment of the
present invention is a polyamic acid derivative having a repeating unit
represented by general formula (1) given above. The polyamic acid
derivative, which is a precursor of a polyimide, can be synthesized by any
of the two methods described below.
In the first method, a compound represented by general formula (4) given
below is formed in the first stage by the reaction between a
tetracarboxylic dianhydride represented by general formula (3) given below
and any of an alcohol compound, amine compound and alkoxide having at
least one hydroxyl group bonded directly to an aromatic ring:
##STR6##
where R.sup.1, R.sup.3 and R.sup.4 are equal to those included in general
formula (1).
In this stage, the molar ratio of the tetracarboxylic dianhydride to the
additive should be set at about 1:1 to 1:2.
In the second stage, a reaction is carried out in an organic solvent among
the compound represented by general formula (4), a diamine represented by
general formula (5) given below, and a dehydrating agent:
NH.sub.2 --R.sup.2 --NH.sub.2 (5)
where R.sup.2 is equal to that included in general formula (1).
In this state, the molar ratio of the reactants should be set at about
1:1:2 (or more).
As a result, a polyamic acid derivative having a repeating unit represented
by general formula (1) is synthesized by the polyamidation of the compound
represented by general formula (4) and the diamine represented by general
formula (5).
The tetracarboxylic dianhydride represented by general formula (3), which
is used in the first stage reaction, is not particularly restricted in the
present invention. To be more specific, the tetracarboxylic dianhydride
used in the present invention includes, for example, pyromellitic
dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride
(BTDA), 1,4,5,8-naphthalene tetracarboxylic dianhydride,
2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene
tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic
dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride,
2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-benzophenone
tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane
dianhydride, 2,2-bis[5-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride,
2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride,
bis(3,4-dicarboxyphenyl)sulfonic dianhydride,
bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)methane
dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, butane
tetracarboxylic dianhydride, 2,2'-(3,4-dicarboxyphenyl)hexafluoropropane
dianhydride, bis (3,4-dicarboxyphenyl)dimethylsilane dianhydride, and
bis(3,4-dicarboxyphenyl)tetramethyldisiloxane dianhydride. These
tetracarboxylic dianhydrides can be used singly or in combination.
In the first stage, the reaction is carried out between the tetracarboxylic
dianhydride given above and an alcohol compound, amine compound, phenol
compound or alkoxide given below. To be more specific, the alcohol
compound used in the first stage reaction is represented by general
formula (6) given below:
R.sup.7 --OH (6)
where R.sup.7 --O-- is equal to R.sup.3 or R.sup.4 defined previously.
R.sup.7 -- in general formula (6) represents an organic group having at
least one hydroxyl group bonded to an aromatic ring. The specific alcohol
compounds used in the present invention include, for example,
2-hydroxybenzyl alcohol, 3-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol,
2-hydroxyphenyl ethyl alcohol, 3-hydroxyphenyl ethyl alcohol,
4-hydroxyphenyl ethyl alcohol, 4-hydroxyphenyl-3-propanol,
4-hydroxyphenyl-4-butanol, and hydroxynaphthyl ethyl alcohol. In the
present invention, it is particularly desirable to use an alcohol compound
represented by general formula (7) given below:
##STR7##
where, p is a positive integer, preferably, integer of 1 to 4.
The amine compound used in the first stage reaction is the primary or
secondary amine represented by general formula (8) given below:
R.sup.8 --N(R.sup.9)H (8)
where R.sup.8 --N(R.sup.9) is equal to R.sup.3 or R.sup.4 defined
previously, and R.sup.9 represents hydrogen or a monovalent organic group.
R.sup.8 -- included in general formula (8) given above represents an
organic group having at least one hydroxyl group bonded to an aromatic
ring. Specific amine compounds used in the present invention include, for
example, 2-aminophenol, 3-aminophenol, 4-aminophenol, 4-amino-4'-hydroxy
diphenylethane, 4-amino-4'-hydroxy diphenylether,
2-(4'-aminophenyl)-2-(3'-hydroxyphenyl)propane,
2-(4'-aminophenyl)-2-(3'-hydroxyphenyl)hexafluoropropane,
2-(3'-aminophenyl)-2-(3'-hydroxyphenyl)propane,
2-(4'-aminophenyl)-2-(4'-hydroxyphenyl)propane, and
2-(4'-aminophenyl)-2-(4'-hydroxyphenyl)hexafluoropropane. Particularly
desirable is a primary or secondary amine represented by general formula
(9) given below:
##STR8##
where, R.sup.9 represents hydrogen or a monovalent organic group, and q is
a positive integer, preferably, an integer of 0 to 4.
The alkoxide used in the first stage reaction is provided by, for example,
an sodium alkoxide or potassium alkoxide of the alcohol compound
represented by general formula (6) described previously.
In the first stage, the reaction between the tetracarboxylic dianhydride
and any of the alcohol compound, the amine compound and the alkoxide
described above is carried out at room temperature or at about 25.degree.
to 200.degree. C. A solvent may or may not be used in the reaction. Also,
a catalyst may or may not be used in the reaction. In the case of using
the alcohol compound represented by general formula (6), the primary or
secondary amine represented by general formula (8) or the alkoxide noted
above in the first stage reaction, produced is a compound which is
represented by general formula (10) given below, which is included in the
general formula (4) described previously:
##STR9##
where X* is --O-- or --N(R.sup.9)--, R* is R.sup.7, R.sup.8 defined
previously or hydrogen, at least one of two R* groups being not hydrogen.
On the other hand, the diamine represented by general formula (5), which is
used in the second stage reaction, is not particularly restricted. The
specific diamine used in the present invention include, for example,
aromatic diamines such as m-phenylenediamine, p-phenylenediamine,
2,4-tolylenediamine, 3,3'-diaminodiphenylether,
4,4,'-diaminodiphenylether, 3,4'-diaminodiphenylether,
3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone,
3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenylmethane,
4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane,
4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ketone,
4,4'-diaminodiphenyl ketone, 3,4'-diaminodiphenyl keone,
2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane,
1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene,
1,4-bis(4-aminophenoxy)benzene, 4-methyl-2,4-bis(4-aminophenyl)-1-pentene,
4-methyl-2,4-bis(4-aminophenyl)-2-pentene,
1,4-bis(.alpha.,.alpha.-dimethyl-4-aminobenzyl)benzene,
imino-di-p-phenylenediamine, 1,5-diaminonaphthalene,
2,6-diaminonaphthalene, 4-methyl-2,4-bis(4-aminophenyl)pentane, 5 (or
6)-amino-1-(4-aminophenyl)-l,3,3-trimethylindane,
bis(p-aminophenyl)phosphine oxide, 4,4'-diamino azobenzene,
4,4'-diaminodiphenylurea, 4,4'-bis(4-aminophenoxy)biphenyl,
2,2-bis[4-(4-aminophenoxy)phenyl]propane,
2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane,
2,2-bis[4-(3-aminophenoxyphenyl]benzophenone,
4,4'-bis(4-aminophenoxy)diphenyl sulfone, 4,4'-bis[4-.alpha.,.alpha.
-dimethyl-4-aminobenzyl)phenoxy]benzophenone,
4,4'-bis[4-(.alpha.,.alpha.-dimethyl-4-aminobenzyl)phenoxy]diphenyl
sulfone, bis(4-aminophenyl)dimethylsilane, and
bis(4-aminophenyl)tetramethylsiloxane. It is also possible to use
derivative of these aromatic diamines, in which at least one substituent
selected from the group consisting of chlorine, fluorine, bromine, methyl,
methoxy, cyano and phenyl is substituted for the hydrogen atom bonded to
the aromatic ring of the aromatic diamine. Further, it is possible to use
3,5-diamino-1-hydoxybenzene, 3,3'-dihydroxy-4,4'-diaminobiphenyl,
4,4'-dihydroxy-3,3'-diaminobiphenyl,
2,2-bis(4-amino-3-hydroxyphenyl)propane,
bis(3-amino-4-hydroxyphenyl)sulfide, bis(3-amino-4-hydroxyphenyl)sulfone,
bis(3-amino-4-hydroxyphenyl)methane, bis(4-amino-3-hydroxyphenyl)methane,
2,2-bis(4-amino-3-hydroxyphenyl)hexafluoropropane,
2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane,
2-(3-hydroxy-4-aminophenyl)-2-(3-amino-4-hydroxyphenyl)hexafluoropropane,
bis(p-aminophenyl)tetramethyldisiloxane,
bis(.gamma.-aminopropyl)tetramethyldisiloxane,
1,4-bis(.gamma.-aminopropyldimethylsilyl)benzene,
bis(4-aminobutyl)tetramethyldisiloxane,
bis(.gamma.-aminopropyl)tetraphenyldisiloxane, 4,4'-diaminobiphenyl,
phenylindanediamine, 3,3'-dimethoxy-4,4'-diaminobiphenyl,
3,3'-dimethyl-4,4'-diaminobiphenyl, o-toluidine sulfone,
bis(4-aminophenoxyphenyl)sulfone, bis(4-aminophenoxyphenyl)sulfide,
1,4-bis(4-aminophenoxyphenyl)benzene,
1,3-bis(4-aminophenoxyphenyl)benzene, 9,9-bis(4-aminophenyl)anthracene
(10), 9,9-bis(4-aminophenyl)fluorene, 4,4'-di-(3-aminophenoxy)diphenyl
sulfone, 4,4'-diaminobenzamilide and the compound represented by a formula
given below;
##STR10##
where l is an integer of 2 to 12.
These diamines can be used singly or in combination.
The dehydrating agent used in the second stage reaction includes, for
example, sulfuric acid, hydrochloric acid, p-toluene sulfonic acid, cobalt
acetate, manganese acetate, stannous chloride, stannic chloride,
polyphosphate, triphenyl phosphite, bis-o-phenylene phosphate,
N,N'-(phenylphosphino)bis[2(3H)-benzothizolone], a carbodimide derivative
represented by general formula R--N.dbd.C.dbd.N--R' and, preferably,
dicyclohexyl carbodiimide (DCC).
In general, a non-protogenic polar solvent is used as an organic solvent in
the synthesis of the resin component having a repreating unit represented
by general formula (1) because the non-protogenic polar solvent is
advantageous in the polymer synthesis. In the synthesis of the polyamic
acid derivative used in the present invention, however, it is also
possible to use an aromatic hydrocarbon, tetrahydrofuran, dioxane, etc. as
a solvent. The specific compounds of the solvent used in the present
invention include, for example, ketone series solvents such as
cyclohexanone, acetone, methyl ethyl ketone, and methyl isobutyl ketone;
cellosolve series solvents such as methyl cellosolve, methyl cellosolve
acetate, ethyl cellosolve acetate, and butyl cellosolve acetate; ester
series solvents such as ethyl acetate, butyl acetate, and isoamyl acetate;
ether series solvents such as tetrahydrofuran and dioxane; other solvents
such as N,N-dimethylformamide, N,N-dimethylacetoamide,
N-methyl-2-pyrrolidone, N-methyl-.epsilon.-caprolactam,
.gamma.-caprolactone, sulfolane, N,N,N',N'-tetramethylurea,
hexamethylphosphoamide, toluene and xylene. These solvents may be used
singly or in combination.
The second stage reaction can be carried out under cooling or heating,
i.e., under the temperature falling with a range of between -20.degree.
and 100.degree. C., for about 30 minutes to 24 hours, preferably for about
1 to 8 hours, more preferably for 4 to 8 hours.
In the first method of synthesizing a polyamic acid derivative having a
repeating unit represented by general formula (1), a monomer (carboxylic
acid derivative) having a substituent (which corresponds to the alcohol
compound, amine compound or alkoxide described previously) introduced into
the carboxylic acid is formed in the first stage reaction. Then, in the
second stage reaction, a polymer chain (polyamic acid derivative) having
the substituent introduced into the side chain is formed by the
polycondensation reaction between the monomer formed in the first stage
reaction and the diamine described previously. In short, the first method
of synthesizing the polyamic acid derivative is featured in that the
reaction proceeds in the order of the substituent introduction and, then,
the polymerization.
In the second method of synthesizing a polyamic acid derivative having a
repeating unit represented by general formula (1), which is a resin
component of the photosensitive resin composition according to the first
embodiment of the present invention, a polymerization reaction is carried
out in the first stage between the tetracarboxylic dianhydride represented
by general formula (3) and the diamine represented by general formula (5).
The molar ratio of the tetracarboxylic dianhydride to the diamine should
be set at about 1.1:1.0 to 1.0:1.1, preferably 1.0:1.0. As a result,
formed is a polyamic acid having a repeating unit represented by general
formula (11) given below:
##STR11##
In the second stage, reaction is carried out within an organic solvent
among the polyamic acid having a repeating unit represented by general
formula (11) noted above, an alcohol compound, amine compound or alkoxide
having at least one hydroxyl group directly bonded to the aromatic ring as
described previously, and the dehydrating agent. In this stage, the molar
ratio of the reactants should be set at about 1:1:1 to 1:2:2 (the molar
amount of the polyamic acid having a repeating unit represented by general
formula (11) calculated in terms of the tetracarboxylic acid units). In
this stage, a dehydrating condensation reaction takes place between the
polyamic acid having a repeating unit represented by general formula (11),
and the alcohol compound, amine compound or alkoxide. As a result, the
substituent is introduced into the side chain (carboxyl group) of the
repeating unit (11) so as to form a polyamic acid derivative having a
repeating unit represented by general formula (1).
Any kind of the tetracarboxylic dianhydride represented by general formula
(3) and the diamine represented by general formula (5) can be used in the
first stage reaction of the second method as far as these tetracarboxylic
dianhydride and diamine can be used in the first method of synthesizing
the polyamic acid derivative described previously.
The polymerization reaction in the first stage of the second method can be
carried out by any of the solution polymerization method, interfacial
polymerization method and melt polymerization method. The organic solvent
which can be used in the first method of synthesizing a polyamic acid
derivative can also be used as a solvent in the solution polymerization
method.
In the case of using the solution polymerization method in the first stage
of the second method, the reaction temperature should be set at
-60.degree. to 150.degree. C. If the reaction temperature is lower than
-60.degree. C., the reaction rate is very low. In this case, it is
necessary to carry out the polymerization reaction for a long time. This
is disadvantageous in the industrial manufacture of the polyamic acid
derivative where the reaction temperature exceeds 150.degree. C., however,
side reactions tend to take place. Also, traces of water contained as an
impurity in the reaction system brings about hydrolysis of the product
polyamic acid having a repeating unit represented by general formula (11).
It follows that the desired polymerization reaction is inhibited, and the
molecular weight of the resultant polyamic acid having a repeating unit
represented by general formula (11) tends to be lowered. Preferably, the
solution polymerization should be carried out at a temperature falling
within a range of between -20.degree. C. and 60.degree. C.
In the case of employing the solution polymerization reaction method in the
first stage, the reaction should be carried out for 30 minutes to 24
hours, preferably for 1 to 8 hours. If the reaction time is shorter than
30 minutes, the polymerization reaction fails to proceed sufficiently. If
the reaction time exceeds 24 hours, however, no industrial merit can be
obtained. Preferably, the reaction should be carried out for 1 to 8 hours.
More preferably, the reaction should be carried out for 4 to 6 hours in
order to avoid the difficulties noted above, i.e., the undesired side
reactions and the hydrolysis, which is caused by an impurity, of the
polyamic acid having a repeating unit represented by general formula (11).
In the second stage reaction included in the second synthesizing method
described above, it is possible to use the compounds which can be used in
the first method of synthesizing the polyamic acid derivative with respect
to any of the alcohol compound, amine compound, and alkoxide having at
least one hydroxyl group bonded to the aromatic ring, dehydrating agent
and organic solvent.
In the second stage reaction, the amount of any of the alcohol compound,
amine compound, and alkoxide is determined to fall within a range of
between 1 mol and 4 mols depending on the reactivity of the specific
compound used relative to 1 mol of the tetracarboxylic dianhydride
represented by general formula (3), which is used in the first stage
reaction. It is possible to control the amount of the substituent
introduced into the side chain of the product polyamic acid derivative
represented by general formula (1), i.e., the rate of introduction of the
organic group into R.sup.3 and R.sup.4, by suitably controlling the amount
of the alcohol compound, etc. noted above in accordance with the object
and use of the final photosensitive resin composition. For example, where
the photosensitive resin composition is used for forming a polyimide film
pattern by the lithography technique, it is necessary for the composition
to be soluble in an alkaline solution. In this case, it is desirable to
set the amount of the additive at 2 mols or less relative to 1 mol of the
tetracarboxylic dianhydride represented by general formula (3).
The second stage reaction is carried out under cooling or heating, i.e.,
under temperatures falling within a range of between -60.degree. to
200.degree. C., for about 30 minutes to 24 hours. If the reaction
temperature is lower than -60.degree. C., the reactivity of the
dehydrating condensation reaction is markedly lowered. If the reaction
temperature exceeds 200.degree. C., however, side reactions such as
decomposition and gelation of the main chain of the reactant polyamic acid
having a repeating unit represented by general formula (11) tend to take
place easily. The second stage reaction should be carried out preferably
at -60.degree. to 100.degree. C. for about 1 to 8 hours, more preferably
at -20.degree. to 50.degree. C. for about 4 hours.
As described above, the second method of synthesizing a polyamic acid
derivative having a repeating unit represented by general formula (1)
comprises the first stage reaction for forming a polymer chain (polyamic
acid), and the second stage reaction for introducing the substituent
(which corresponds to the alcohol compound, amine compound and alkoxide)
into side chain of the polymer so as to synthesize the desired polyamic
acid derivative. In short, the second method is featured in that the
reactions proceed in the order of polymerization and, then, introduction
of the substituent, which is opposite to that in the first method. It
follows that, in the second method, the rate of polymerization reaction
carried out in the first stage is promoted because the polymerization
reaction, which is carried out between the acid anhydride and diamine,
proceeds quantitatively. As a result, the formed polymer is enabled to
have a sufficiently large molecular weight. In the first method, however,
the condensation reaction involving the dehydrating agent does not
necessarily proceed quantitatively in the polymerization reaction which is
carried out in the second stage. In addition, since the substituent group
is already bonded to the monomer, the monomer molecule is rendered bulky
depending on the kind of the substituent group. It follows that the rate
of the polymerization reaction tends to be lowered. In other words, the
polymerization degree of the formed polymer tends to be low in some cases.
In the second method, however, the polymer formed by the side reaction,
which is brought about by the dehydrating agent, is partly gelled. As a
result, the polyamide film pattern formed by using the photosensitive
resin composition containing said polymer tends to be lowered in
resolution.
Under the circumstances, it is desirable to synthesize the polyamic acid
derivative by the first method in the case of forming a fine polyimide
film pattern of 10 microns or less.
On the other hand, the polyimide film pattern formed by using the
photosensitive resin composition containing a polymer synthesized by the
second method is excellent in its mechanical strength. It follows that,
where the polyimide film pattern is required to exhibit a high mechanical
strength, it is possible to employ the second method for synthesizing the
polyamic acid derivative.
In the present invention, additional compounds given below can also be used
as compounds for introducing substituent groups into the side chains of
the polyamic acid derivative having a repeating unit represented by
general formula (1), i.e., as compounds reacting with the tetracarboxylic
dianhydride represented by general formula (3) in the first stage of the
first method or as compounds reacting with the polyamic acid represented
by general formula (11) in the second stage of the second method.
Specifically, it is possible to use as such a compound any of an alcohol
compound which does not have a hydroxyl group bonded to the aromatic ring,
an amine compound which does not have a hydroxyl group bonded to the
aromatic ring, an alkoxide which does not have a hydroxyl group bonded to
the aromatic ring, and a phenol compound having only one hydroxyl group
bonded to the aromatic ring together with the alcohol compound, amine
compound and alkoxide having at least one hydroxyl group bonded to the
aromatic ring.
The alcohol compound which does not have a hydroxyl group bonded to the
aromatic ring includes, for example, methanol, ethanol, 1-propanol,
isopropyl alcohol, 1-butanol, 2-butanol, isobutanol, t-butanol,
1-pentanol, 1-hexanol, benzyl alcohol, methylbenzyl alcohol, cynnamyl
alcohol, methoxybenzyl alcohol, allyl alcohol, chrotyl alcohol, and
2-hydroxyethyl methacrylate.
The amine compound which does not have a hydroxyl group bonded to the
aromatic ring includes, for example, methyl amine, ethyl amine, propyl
amine, butyl amine, pentyl amine, hexyl amine, aniline, toluidine, ethyl
aniline, and benzyl amine.
The alkoxide which does not have a hydroxyl group bonded to the aromatic
ring includes, for example, sodium alkoxide and potassium alkoxide of the
alcohol compounds noted above.
Further, the phenol compound noted above includes, for example, phenol,
cresol, xylenol, butyl phenol, allyl phenol, and methoxy phenol.
In the case of using the compound which does not have a hydroxyl group
bonded to the aromatic ring or the particular phenol compound noted above,
the amount of the particular compound should desirably be about 80 mol %
or less based on the total amount of the compounds used for introducing
the substituent group into the side chains of the polyamic acid
derivative. If the amount noted above is larger than 80 mol %, the
solubility of the photosensitive resin composition in a developing
solution is lowered, resulting in a low resolution of the polyimide film
pattern formed by using the composition. More preferably, the amount of
the particular compound should be 60 mol % or less.
In this case, it is possible for the particular polyamic acid derivative
noted above and the polyamic acid derivative having the organic group, in
which a hydroxyl group is bonded to the aromatic ring, introduced into the
side chain to form a mixture in the resin component of the photosensitive
resin composition of the present invention. It is also possible for these
two kinds of the polyamic acid derivatives to form a copolymer.
The polyamic acid derivative having a repeating unit represented by general
formula (1) is purified as follows. In the first step, methanol, ethanol,
water or the like, which is used in an amount of about 1 to 2 mols per mol
of the dehydrating agent, is added to the reaction solution of the
polyamic acid derivative, and the system is stirred for 1 to 4 hours so as
to bring about reaction of the unreacted dehydrating agent and, thus, to
form a precipitate. Then, the precipitate is removed outside the system by
means of filtering. The reaction solution thus prepared is slowly added to
methanol, ethanol or water in an amount of 5 to 100 times as much as the
amount of the reaction solution so as to precipitate a polymer. The
resultant polymer is separated out by means of filtering and, then, washed
with methanol, ethanol or water. Further, the washed polymer is dried
under vacuum at 60.degree. C. so as to isolate and purify the polyamic
acid derivative.
In the photosensitive resin composition according to the second embodiment
of the present invention, the resin component is provided by a mixture
comprising a polyamic acid derivative having a repeating unit represented
by general formula (1) given above and a polyamic acid having a repeating
unit represented by general formula (2) given above. The polyamic acid
derivative having a repeating unit represented by general formula (1) can
be synthesized as in the polyamic acid derivative contained in the
photosensitive resin composition according to the first embodiment of the
present invention. Also, the polyamic acid derivative noted above can be
synthesized by using the compounds similar to those used in the first
embodiment of the present invention described previously.
On the other hand, the polyamic acid having a repeating unit represented by
general formula (2) can be synthesized by any of the two methods described
below.
In the first method, reaction between a tetracarboxylic dianhydride
represented by general formula (12) given below and a diamine represented
by general formula (13) given below is carried out within a suitable
solvent. The reaction should be carried out at -20.degree. C. to
20.degree. C., preferably at -5.degree. C. to 10.degree. C., so as to
obtain a polyamic acid having a repeating unit represented by general
formula (2):
##STR12##
where R.sup.5 and R.sup.6 are as already defined in general formula (2).
In the first method, it is possible to use compounds similar to those of
the tetracarboxylic dianhydride represented by general formula (3), the
diamine represented by general formula (5) and the solvent used in the
synthesis of the polyamic acid derivative having a repeating unit
represented by general formula (1) as the tetracarboxylic dianhydride
represented by general formula (12), the diamine represented by general
formula (13) and the solvent, respectively.
In the second method, any one of a monoamine represented by general formula
(14) given below and a dicarboxylic anhydride represented by general
formula (15) given below is reacted with the tetracarboxylic dianhydride
represented by general formula (12) and the diamine represented by general
formula (13) in the presence of an organic solvent. In this case, a
polycondensation reaction is carried out within the organic solvent so as
to obtain a polyamic acid having a repeating unit represented by general
formula (2):
H.sub.2 N--A (14)
where, A represents a monovalent organic group.
##STR13##
where, B represents a divalent organic group.
In the case of using the monoamine represented by general formula (14), the
tetracarboxylic dianhydride represented by general formula (12) and the
diamine represented by general formula (13) in the polycondensation
reaction which is carried out in the second method, synthesized is a
polyamic acid represented by general formula (16) given below as a
polyamic acid having a repeating unit represented by general formula (2):
##STR14##
where r represents a positive integer.
On the other hand, in the case of using the dicarboxylic anhydride
represented by general formula (15), the tetracarboxylic dianhydride
represented by general formula (12) and the diamine represented by general
formula (13) in the polycondensation reaction which is carried out in the
second method, synthesized is a polyamic acid represented by general
formula (17) given below as a polyamic acid having a repeating unit
represented by general formula (2):
##STR15##
where s represents a positive integer.
The monoamine represented by general formula (14) includes, for example,
m-aminodiphenyl, p-aminodiphenyl, m-aminodiphenyl ether, p-aminodiphenyl
ether, aniline, o-anisidine, m-anisidine, p-anisidine,
p-aminobenzaldehyde, o-toluidine, m-toluidine and p-toluidine.
The dicarboxylic anhydride represented by general formula (15) includes,
for example, phthalic anhydride, hexahydrophthalic anhydride,
methylnadicanhydride, 4-methylhexahydrophthalic anhydride,
methyltetrahydrophthalic anhydride, and maleic anhydride.
In the case of employing the second method for the synthesis of the
polyamic acid having a repeating unit represented by general formula (2),
it is possible to use as the tetracarboxylic dianhydride represented by
general formula (12) and the diamine represented by general formula (13)
the compounds similar to those of the tetracarboxylic dianhydride
represented by general formula (3) and the diamine represented by general
formula (5), respectively, which are used for the synthesis of the
polyamic acid derivative having a repeating unit represented by general
formula (1).
Particularly, it is desirable in the present invention to use as the
diamine represented by general formula (13) a siloxane compound because
the use of the siloxane compound permits improving the adhesion between
the polyimide film, which is finally obtained, and a semiconductor
substrate.
The organic solvent used for the polycondensation reaction utilized in the
second method of synthesizing a polyamic acid having a repeating unit
represented by general formula (2) includes, for example,
N,N-dimethylformamide, N,N-dimethylacetoamide, N-methyl-2-pyrrolydone,
N-methyl-.epsilon.-caprolactam, .gamma.-butylolactone, sulfolane,
N,N,N',N'-tetramethylurea and hexamethylphosphoamide.
In the second method of synthesizeing a polyamic acid having a repeating
unit represented by general formula (2), it is necessary to set the ratio
of the sum of the monoamine represented by general formula (14) and the
diamine represented by general formula (13) to the sum of the dicarboxylic
anhydride represented by general formula (15) and the tetracarboxylic
dianhydride represented by general formula (12) as follows. Specifically,
the equivalent ratio of the amino group (--HN.sub.2) to the acid anhydride
group
##STR16##
should be about 100:100. Further, in the second method, the reaction
should be carried out at -15.degree. to 30.degree. C. for 10 minutes to 20
hours.
In order to improve the coating capability of the photosensitive resin
composition or the polyamic acid on the surface of a semiconductor
substrate, it is desirable for the resultant polyamic acid having a
repeating unit represented by general formula (2) to have a logarithmic
viscosity, as measured under a polymer concentration of 0.5 g/dl within a
N-methyl-2-pyrrolidone solvent maintained at 30.degree. C., of 0.4 to 1.0
dl/g, preferably 0.5 to 0.9 dl/g. In order to control the logarithmic
viscosity of the polyamic acid having a repeating unit represented by
general formula (2) to fall within the range noted above in the second
method of synthesizing the polyamic acid having a repeating unit
represented by general formula (2), it is necessary to control the mixing
ratio of the raw materials as described below.
In the case of synthesizing a polyamic acid represented by general formula
(16) by utilizing the polycondensation reaction among the monoamine
represented by general formula (14), the tetracarboxylic dianhydride
represented by general formula (12) and the diamine represented by general
formula (13), the molar ratio of the monoamine (14) to the diamine (13)
should be 0.01 to 0.2:0.9 to 0.995, preferably 0.02 to 0.06:0.97 to 0.99.
If the mixing amount of the monoamine (14) is unduly large, the
logarithmic viscosity of the synthesized polyamic acid (16) is lowered,
resulting in failure to obtain a cured film having a smooth surface. On
the other hand, if the mixing amount of the monoamine (14) is unduly
small, it is impossible to obtain a sufficient effect on treating the
molecular terminal of the polyamic acid (16), with the result that a
difficulty is brought about in terms of workability.
In the case of synthesizing the polyamic acid represented by general
formula (17) by utilizing the polycondensation reaction among the
dicarboxylic anhydride (15), the tetracarboxylic dianhydride (12) and the
diamine (13), the molar ratio of the dicarboxylic anhydride (15) and the
tetracarboxylic dianhydride (12) should be 0.01 to 0.2:0.9 to 0.995,
preferably 0.02 to 0.06:0.97 to 0.99. If the mixing amount of the
dicarboxylic anhydride (15) is unduly large, the logarithmic viscosity of
the synthesized polyamic acid (17) is lowered, resulting in failure to
obtain a cured film having a smooth surface. On the other hand, if the
mixing amount of the dicarboxylic anhydride (15) is unduly small, it is
impossible to obtain a sufficient effect on treating the molecular
terminal of the polyamic acid (17), with the result that a difficulty is
brought about in terms of workability.
In the case of using a siloxane compound as a diamine (13) in the synthesis
of the polyamic acid (16) or (17), it is desirable to use the siloxane
compound in an amount of 0.01 to 20 mol % based on the total amount of the
amine compounds (monoamine being calculated in terms of diamine). If the
mixing amount of the siloxane compound exceeds 20 mol %, the heat
resistance of the final polyimide film tends to be lowered. On the other
hand, if the mixing amount of the siloxane compound is smaller than 0.01
mol %, it is impossible to obtain the effect of improving adhesion between
the polyimide film and the semiconductor substrate.
In the present invention, it is desirable to employ the second method,
which uses the monoamine (14) and the dicarboxylic anhydride (15), for
synthesizing the polyamic acid having a repeating unit represented by
general formula (2), because the second method permits stably synthesizing
a polyamic acid of a desired chemical structure.
The photosensitive resin composition according to the second embodiment of
the present invention contains as resin components both a polyamic acid
derivative having a repeating unit represented by general formula (1) and
a polyamic acid having a repeating unit represented by general formula
(2). The mixing amount of the polyamic acid derivative should be 20 to 98
parts by weight based on 100 parts by weight of the total amount of the
resin components, preferably 30 to 95 parts by weight. If the mixing
amount of the polyamic acid derivative is smaller than 20 parts by weight,
the rate of dissolution in a developing solution is increased in both the
light exposed portion and the nonexposed portion in the case of patterning
a polyimide film, which is formed by using the photosensitive resin
composition of the present invention, by means of photolithography or the
like. It follows that a contrast of the desired relief image is lowered.
It should also be noted that the polyamic acid serves to improve the
mechanical strength of the final polyimide film. In order to obtain a
sufficient effect of improving the mechanical strength, it is necessary to
use at least 20 parts by weight of the polyamic acid.
As in the photosensitive resin composition according to the first
embodiment of the present invention, it is possible for the photosensitive
resin composition according to the second embodiment of the present
invention to contain a polyamic acid derivative having a substituent
group, which does not have a hydroxyl group bonded to the aromatic ring,
introduced into the side chain.
The photosensitive resin composition according to the third embodiment of
the present invention contains as a resin component a polyamic acid
derivative having a copolymer structure including a repeating unit
represented by general formula (1) given above and a repeating unit
represented by general formula (2) given above. It is possible to
synthesize the polyamic acid derivative having a copolymer structure by a
method similar to the first method of synthesizing the polyamic acid
derivative contained in the photosensitive resin composition according to
the first embodiment of the present invention.
Specifically, in a first stage, the tetracarboxylic dianhydride (3) is
reacted with any of the alcohol compound having at least one hydroxyl
group bonded to the aromatic ring, the amine compound having at least one
hydroxyl group bonded to the aromatic ring, and the alkoxide having at
least one hydroxyl group bonded to the aromatic ring so as to obtain the
compound represented by general formula (4). The molar ratio of the
tetracarboxylic dianhydride to the additive should be set at 1:1 to 1:2.
The reaction may be carried out in the presence or absence of a solvent at
room temperature or under heating.
In a second stage, reaction among the compound (4), the diamine (5) and the
dehydrating agent is carried out within an organic solvent. The molar
ratio of these reactants should be set at s: (s+t): 2s or more (s and t
being a positive integer). The reaction may be carried out under cooling
or heating condition for about 1 to 8 hours, preferably for at least 4
hours.
Further, in a third stage, t mol of the tetracarboxylic dianhydride (3) is
added to the reaction solution prepared in the second stage so as to carry
out a reaction at 0.degree. to 20.degree. C. for about 1 to 8 hours,
preferably for at least 4 hours. As a result, prepared is a polyamic acid
derivative of a copolymer structure having the repeating units represented
by both general formula (1) and general formula (2). In this case, R.sup.1
and R.sup.2 included in general formulas (1) and (2) are equal to R.sup.5
and R.sup.6, respectively.
In the second stage, the compound (4) fails to react completely with the
diamine depending on the kind of the dehydrating agent used. In some
cases, unreacted diamine (5) remains in the reaction product even if t
mols of the tetracarboxylic dianhydride (3) is added in the third stage.
If unreacted diamine remains in the photosensitive resin composition, the
stability tends to be impaired with respect to the photosensitive agent,
in particular o-quinone diazide compound, which will be described herein
later. In order to decrease the amount of the remaining unreacted diamine,
it is possible to add more than t mols of the tetracarboxylic dianhydride
in the third stage. Alternatively, it is possible to carry out a
equivalent reaction between the compound (4) and diamine (5) in the second
stage, followed by adding an excessive amount of the tetracarboxylic
dianhydride (3) in the third stage in order to treat the unreacted
diamine. It is possible to increase the molecular weight of the resin
component by allowing the tetracarboxylic dianhydride (3) to react with
the unreacted reactant.
In the synthesis of the resin component contained in the photosensitive
resin composition according to the third embodiment of the present
invention, it is possible to use any of the compounds used in the
synthesis of the resin component contained in the photosensitive resin
compositions according to the first and second embodiments of the present
invention with respect to any of the tetracarboxylic dianhydride (3), the
alcohol compound having at least one hydroxyl group bonded to the aromatic
ring, the amine compound having at least one hydroxyl group bonded to the
aromatic ring, the alkoxide having at least one hydroxyl group bonded to
the aromatic ring, the diamine (5), the dehydrating agent and any of the
solvents.
In the synthesis of the resin component contained in the photosensitive
resin composition according to the third embodiment of the present
invention, it is possible to use an alcohol compound which does not have a
hydroxyl group bonded to the aromatic ring, an amine compound which does
not have a hydroxyl group bonded to the aromatic ring, alkoxide which does
not have a hydroxyl group bonded to the aromatic ring, or a phenol
compound having only one hydroxyl group bonded to the aromatic ring
together with the alcohol compound having at least one hydroxyl group
bonded to the aromatic ring, the amine compound having at least one
hydroxyl group bonded to the aromatic ring, the alkoxide having at least
one hydroxyl group bonded to the aromatic ring, as in the photosensitive
resin composition according to the first embodiment of the present
invention.
The ratio (s/t) in the amount of the repeating units (1) to the repeating
units (2) need not be specified in the copolymer structure of the resin
component because properties of the resin film which is finally obtained
differ depending on the raw material resins used. However, in the case
where the photosensitive resin composition is of positive type, in which
light-exposed portion is dissolved in an alkaline developing solution
depending on the kind of the photosensitive agent described later, the
number of carboxyl groups of the polyamic acid is increased with increase
in the value of t noted above, with the result that the solubility in the
alkaline developing solution is increased even in the non-exposed portion,
too. It follows that it is impossible to obtain a sufficiently large
difference in the solubility in the alkaline developing solution between
the exposed portion and the non-exposed portion in the stage of
development. On the other hand, if the value of t is unduly small, some
portion of the diamine (5) tends to remain unreacted, with the result that
the stability of the photosensitive agent tends to be impaired, as
described previously. It follows that it is desirable for the value of s/t
to fall within a range of between 2 and 20.
The order of arrangement of the repeating units (1) and the repeating units
(2) in the copolymer structure of the resin component is not particularly
restricted in the photosensitive resin composition according to the third
embodiment of the present invention. In other words, it is possible for
the polyamic acid derivative of the copolymer structure to be any of an
alternate copolymer, random copolymer, and block copolymer.
The photosensitive resin composition of the present invention contains a
photosensitive agent. In the present invention, the photosensitive agent
can be commonly used for the photosensitive resin compositions of the
first, second and third embodiments. The specific compounds used as the
photosensitive agent in the present invention include, for example,
o-quinone diazide compound, azide compound and diazo compound.
In the case of using o-quinone diazide compound, compounds having at least
one o-quinone diazide group in the molecule, e.g., compounds QD-1 to QD-15
shown in Table A, can be used singly or in combination. It is particularly
desirable to use as the photosensitive agent aromatic esters of
o-naphthoquinone diazide sulfonic acid including, for example,
1,2-naphthoquinone diazide sulfonic acid esters of 2,3,4-trihydroxy
benzophenone such as compounds QD-1 and QD-2 shown in Table A, and
1,2-naphthoquinone diazide sulfonic acid esters of 2,3,4,4'-tetrahydroxy
benzophenone such as compounds QD-4 and QD-5 shown in Table A.
For example, compound QD-4, i.e., 1,2-naphthoquinone diazide-5-sulfonic
acid ester of 2,3,4,4'-tetrahydroxybenzophenone, is suitable for use as a
photosensitive agent for the exposure to g-rays. Compound QD-5, i.e.,
1,2-naphthoquinone diazide-4-sulfonic acid ester of
2,3,4,4'-tetrahydroxybenzophenone, is suitable for use as a photosensitive
agent for the exposure to an ultraviolet radiation having a wavelength
shorter than that of g-rays. In the photosensitive agent of
1,2-naphthoquinone diazide-4-sulfonic acid ester of
2,3,4,4'-tetrahydroxybenzophenone, the esterification rate of
2,3,4,4'-tetrahydroxybenzophenone with 1,2-naphthoquinone
diazide-4-sulfonic acid is in general 40 to 100% based on the total number
of hydroxyl groups contained in the benzophenone compound. In other words,
the number of naphthoquinone diazide groups introduced into a single
molecule of 2,3,4,4'-tetrahydroxy benzophenone, which has four hydroxyl
groups, is 1.6 to 4 on the average. It follows that this photosensitive
agent is equal to a mixture of sulfonic acid esters having 1, 2, 3 or 4
naphthoquinone azide compounds.
In the present invention, it is also possible to use 1,2-naphthoquinone
diazide-4-sulfonic acid esters, e.g., compounds QD-16 to QD-51 shown in
Table B, as the o-quinone diazide compound acting as the photosensitive
agent.
These naphthoquinone diazide compounds can be easily prepared by reacting a
naphthoquinone diazide sulfonyl chloride represented by the formula given
below with any of alcohols, phenols or amines so as to remove HCl:
##STR17##
Where an azide compound is used as a photosensitive agent contained in the
photosensitive resin composition of the present invention, compounds A-1
to A-28 shown in Table C can be used singly or in combination.
Where a diazo compound is used as a photosensitive agent in the
photosensitive resin composition of the present invention, it is desirable
to use a diazo compound represented by general formula (18) given below:
##STR18##
where R.sup.10 and R.sup.11, which may be the same or different, represent
substituted or unsubstituted alkyl group having 1 to 20 carbon atoms,
substituted or unsubstituted aryl group, substituted or unsubstituted
alkyl group having 1 to 20 carbon atoms and a silicon atom, or substituted
or unsubstituted aryl group having a silicon atom.
The diazo compound represented by general formula (18) permits forming a
fine polyimide film pattern in the case of using, particularly, a deep
ultraviolet radiation. Specific compounds DA-1 to DA-22 shown in Table D
can be used singly or in combination as the diazo compound represented by
general formula (18).
The photosensitive resin compositions according to the first to third
embodiments of the present invention can be prepared as follows by using
the resin components and the photosensitive agent components described
above.
Specifically, a photosensitive agent is dissolved in a solution of a resin
component synthesized within an organic solvent as described previously so
as to prepare a varnish. It is desirable for the varnish to have a polymer
(resin component) concentration of 5 to 40% by weight.
In preparing the varnish, the addition amount of the photosensitive agent
should be controlled as follows. In the case of the photosensitive resin
composition according to the first or third embodiment of the present
invention, it is desirable to set the amount of the photosensitive agent
at 0.1 to 30 parts by weight based on 100 parts by weight of the amount of
the resin component, i.e., the polyamic acid derivative having a repeating
unit represented (1), or the polyamic acid derivative of a copolymer
structure having a repeating unit (1) and a repeating unit (2). Where the
amount of the photosensitive agent is smaller than 0.1 parts by weight,
the resultant photosensitive resin composition fails to exhibit a
sufficiently high sensitivity to light in the light exposure step. On the
other hand, where the amount of the photosensitive agent is larger than 30
parts by weight, it is impossible to obtain a sufficient difference in
solubility in a developing solution between the exposed portion and the
non-exposed portion of the photosensitive resin composition layer,
resulting in failure to obtain a desired polyimide film pattern.
In the case of using the photosensitive resin composition according to the
second embodiment of the present invention, it is desirable to set the
amount of the photosensitive agent to fall within a range of between 5 and
50 parts by weight, preferably between 10 and 30 parts by weight, based on
the sum of the polyamic acid derivative having a repeating unit (1), the
polyamic acid having a repeating unit (2), and the photosensitive agent,
the sum being set at 100 parts by weight. If the amount of the
photosensitive agent is smaller than 5 parts by weight, the resultant
photosensitive resin composition fails exhibit a sufficiently high
sensitivity to light in the step of light exposure. On the other hand, if
the amount is larger than 50 parts by weight, the residue of the
photosensitive agent component after the development raises a serious
problem.
It is possible to add as desired a photosensitizer, a dye, a surfactant, an
alkali-soluble resin, etc. to the photosensitive resin composition of the
present invention. The alkali-soluble resin, which is not particularly
restricted in the present invention, includes, for example, poly-p-vinyl
phenol, poly-o-vinyl phenol, poly-m-isopropyl phenol, m,p-cresol novolak
resin, xylesol novolak resin, copolymer of p-vinyl phenol and methyl
methacrylate, copolymer of p-isopropenyl phenol and maleic anhydride,
polymethacrylic acid, and polymers having the repeating units shown in
Table E.
Let us describe the functions of the photosensitive resin compositions
according to the first to third embodiments of the present invention with
reference to the process of forming a polyimide passivation film or a
polyimide interlayer insulting film using the compositions.
The photosensitive resin composition of the present invention performs
different functions in the steps of exposure and development depending on
the chemical structure of the resin component used, the kind of the
photosensitive agent used, and the pattern forming method. The following
description covers the case where o-quinone diazide compound and an azide
compound are used as the photosensitive agent.
Let us describe first the function of the photosensitive resin composition
of the present invention in the case where an o-quinone diazide compound,
i.e., 1,2-naphthoquinone diazide-5-sulfonic acid ester, is used as the
photosensitive agent. In this case, the photosensitive resin compositions
according to the first to third embodiments of the present invention
perform substantially the same function.
In the first step, the photosensitive resin composition according to any of
the first to third embodiments of the present invention, which contains
1,2-naphthoquinone diazide-5-sulfonic acid ester as the photosensitive
agent, is filtered so as to remove fine impurities from the composition,
followed by coating a semiconductor substrate with the composition by
means of the rotary coating method or the dipping method. Then, the
coating is heated and dried (baked) so as to form a photosensitive resin
composition layer. It should be noted that the photosensitive resin
composition of the present invention exhibits an excellent solubility in a
solvent. This facilitates the coating process and, thus, the composition
is suitable for forming a thick layer.
In the next step, the photosensitive resin composition layer is pre-cured
at 60.degree. to 100.degree. C., followed by selectively exposing the
composition layer through a desired mask pattern to an energy beam such as
an X-ray, visible light, infrared radiation, ultraviolet radiation, and an
electron beam (exposure step). In this step, the o-naphthoquinone diazide
sulfonic acid ester portion (19) of the photosensitive agent in the
exposed portion of the photosensitive resin composition is converted into
a ketene represented by general formula (20) given below by the
photochemical reaction and water within the system, as shown below:
##STR19##
where R' represents a monovalent organic group.
After the light exposure step, a baking treatment is applied to the
photosensitive resin composition layer at about 90.degree. to 200.degree.
C. for about 5 seconds to 60 minutes. By this baking treatment, the ketene
(20) formed as a result of the exposure reacts with the active hydrogen
contained in the resin component in the exposed portion so as to crosslink
the polymer chains. On the other hand, the o-naphthoquinone diazide
sulfonic acid ester contained in the resin composition is partially
decomposed by the baking treatment in the non-irradiation portion
(non-exposed portion).
In the next step, a development is applied to the photosensitive resin
composition layer after the baking treatment by means of, for example, a
dipping method using an alkaline aqueous solution or a spraying method
(developing step). The alkaline aqueous solution used in the present
invention includes an inorganic alkaline aqueous solution such as an
aqueous solution of potassium hydroxide or sodium hydroxide and an organic
alkaline aqueous solution such as an aqueous solution of propyl amine,
butylamine, monoethanolamine, ethylenediamine, trimethylenediamine,
trimethylammonium hydroxide, hydrazine, or tetramethylammonium hydroxide.
These alkaline aqueous solutions can be used singly or in combination. It
is also possible to add to these amine compounds a poor solvent for the
photosensitive resin composition of the present invention such as
methanol, ethanol, 2-propanol, ethylene glycol, ethylene cellosolve, butyl
cellosolve, diethylene glycol, ethyl carbitol or water. Alternatively, the
amine compound noted above may be mixed with a solvent used for preparing
the photosensitive resin composition of the present invention such as
N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetoamide, or
dimethylsulfoxide.
The photosensitive agent, i.e., o-naphthoquinone diazide sulfonic acid
ester, is partially decomposed in the non-exposed portion of the
photosensitive resin composition layer, with the result that the
capability of inhibiting the dissolution in an alkaline solution, said
capability being inherent in the photosensitive resin composition, tends
to be lowered or lost. It follows that the non-exposed portion is made
soluble in the alkaline developing solution. In the exposed portion,
however, the resin component is crosslinked as described previously. It
follows that the molecular weight of the resin component is increased and,
thus, the resin component is not dissolved in the alkaline developing
solution. In other words, the exposed portion alone is selectively left
unremoved in the developing step.
As described above, the photosensitive resin composition according to any
of the first to third embodiments of the present invention performs the
function of a negative photosensitive material in some cases, i.e., a
photosensitive material in which the exposed portion is rendered insoluble
in the developing solution in the exposure and developing steps in the
case where a pattern is formed by the steps described above using an
o-naphthoquinone diazide compound, i.e., 1,2-naphthoquinone
diazide-5-sulfonic acid ester, as a photosensitive agent. However, the
function noted above is not necessarily produced in the process of forming
a pattern. It should also be noted that, in the case of using an o-quinone
diazide compound as a photosensitive agent, it is possible to omit the
baking treatment after the light exposure step, i.e., post-exposure baking
(PEB). In the above-described process of forming a pattern, however, the
post-exposure baking is highly effective for partially imidizing the
polymer in the photosensitive resin composition layer so as to control the
dissolving rate of the composition layer in the alkaline developing
solution and to improve the contrast of the finally obtained pattern. In
addition, the post-exposure backing serves to improve the adhesion between
the resin composition layer and the semiconductor substrate, with the
result that the resin composition layer can be prevented from being peeled
off the semiconductor substrate in the developing step.
Further, the post-exposure baking permits forming a satisfactory negative
pattern even in the case of using a photosensitive resin composition
containing as a resin component a polyamic acid derivative which does not
have a substituent group having a hydroxyl group bonded to the aromatic
ring, said substituent group being introduced into the side chain of said
derivative, and as a photosensitive agent component an o-naphthoquinone
diazide compound. To be more specific, the polyamic acid derivative noted
above includes, for example, a polyamic acid derivative which is obtained
in the case of using singly an alcohol compound, amine compound, alkoxide,
each of which does not have a hydroxyl group bonded to the aromatic ring,
or a phenol compound having only one hydroxyl group bonded to the aromatic
ring, as a compound for introducing a substituent group into the side
chain of the polymer in the synthesis of the polyamic acid derivative
described previously.
To reiterate, the post-exposure baking permits forming a satisfactory
negative pattern in the case where the photosensitive resin composition
contains the particular polyamic acid derivative noted above. The
formation of a satisfactory negative pattern is supposed to be derived
from the reactions described below. Specifically, the post-exposure baking
causes the o-naphthoquinone diazide sulfonic acid ester contained in the
resin composition to be partially decomposed so as to form a ketene in the
non-exposed portion of the resin composition layer. The ketene thus formed
is converted into a carboxylic acid by the water in the system, resulting
in an increased solubility of the non-exposed portion in the alkaline
developing solution. It follows that, since a substituent group which does
not have a hydroxyl group bonded to the aromatic ring is introduced into
the side chain, the non-exposed portion is made soluble in the alkaline
developing solution even in the case of using a polyamic acid derivative
which is originally low in its solubility in the alkaline developing
solution. On the other hand, the post-exposure baking permits crosslinking
the resin component in the exposed portion of the resin composition layer
as in the case of using a polyamic acid derivative having a substituent
group, which has a hydroxyl group bonded to the aromatic ring, introduced
into the side chain, with the result that the exposed portion is made
substantially insoluble in the alkaline developing solution. In
conclusion, the exposed portion alone is selectively left unremoved in the
developing step so as to form a satisfactory negative pattern.
Also, where the photosensitive resin composition according to any the first
to third embodiments of the present invention contains an o-quinone azide
as a photosensitive agent, the composition is enabled to perform the
function of a negative photosensitive material by applying various
treatments besides the patterning step involving the post-exposure baking
described above. Further, a negative photosensitivity can be imparted to
the photosensitive resin composition of the present invention, for
example, by adding a basic substance such as imidazole to the resin
composition, by exposing the entire substrate coated with the resin
composition after the exposure step and the post-exposure baking step to
an ultraviolet ray, or by heating the substrate after the exposure step
under a steam atmosphere of ammonia, alkyl amine or the like.
Further, it is possible to apply a rinsing treatment with water, alcohol,
acetone or the like after the development in order to remove the
developing solution residue, followed by applying a baking treatment.
In the photosensitive resin composition of the present invention using an
o-quinone diazide compound as a photosensitive agent, it is particularly
desirable to form a pattern in accordance with the process described
above. In this case, the post-exposure baking is not particularly
required, though the photosensitive resin composition performs a function
different from that describe above in this case.
Specifically, the o-naphthoquinone diazide sulfonic acid ester portion (19)
of the molecule in the exposed portion of the layer of the photosensitive
resin composition of the present invention is converted after the light
exposure step into the ketene (20) by the photochemical reaction and by
the water present in the system, as described previously. Then, a
development is applied to the photosensitive resin composition layer after
the exposure step without applying a baking treatment. The development is
performed by means of a dipping method using an alkaline aqueous solution
or by a spraying method. It should be noted that, in the non-exposed
portion of the photosensitive resin composition layer, the
o-naphthoquinone diazide sulfonic acid ester acts as an dissolution
inhibitor serving to prevent the resin composition from being dissolved in
the alkaline aqueous solution. It follows that the nonexposed portion of
the resin composition layer is made more unlikely to be dissolved in the
developing solution than the polymer alone.
In the exposed portion of the photosensitive resin composition layer,
however, the ketene (20) converted by the photochemical reaction from
o-naphthoquinone diazide sulfonic acid ester as described above is further
converted into a carboxylic acid (21) by the water present in the system,
as shown below:
##STR20##
where R' represents a monovalent organic group.
Since the carboxyl group of the carboxylic acid (21) reacts with the alkali
metal ion or ammonium ion present in the alkaline developing solution so
as to form a salt, with the result that the exposed portion is made
soluble. In other words, the non-exposed portion alone is left unremoved
in the development.
As described above, the photosensitive resin composition according to any
of the first to third embodiments of the present invention is enabled to
perform the function of a positive photosensitive material in which the
exposed portion is made soluble in the developing solution, if the
development is applied without employing the post-exposure baking in the
case where the composition contains an o-quinone diazide compound, i.e.,
1,2-naphthoquinone diazide-5-sulfonic acid ester, as a photosensitive
agent. Where the composition performs the function of a positive
photosensitive material, however, the carboxylic acid (21) formed in the
exposed portion fails to make the exposed portion sufficiently soluble in
the developing solution in some cases. In such a case, the carboxyl group
having a repeating unit represented by general formula (2), which is
contained in the resin component, performs the function similar to that
performed by the carboxyl group of the carboxylic acid (21) noted above,
when it comes to the photosensitive resin composition according to any of
the second and third embodiments of the present invention. Since the
carboxyl group of the repeating unit (2) also forms a alkali salt, the
solubility of the exposed portion of the photosensitive resin composition
in the alkaline developing solution is promoted so as to improve the
resolution of the polyimide film pattern which is finally formed.
As described previously, it is possible to apply a rinsing treatment with
water, alcohol, acetone, etc. after the development in order to remove the
developing solution residue, followed by applying a baking treatment.
As described previously, it is possible for the photosensitive resin
composition according to any of the first to third embodiments of the
present invention to contain an azide compound as a photosensitive agent.
In the case of containing an azide compound as a photosensitive agent, the
photosensitive resin compositions according to the first to third
embodiments of the present invention perform substantially the same
function.
In the first step, a semiconductor substrate is coated with a
photosensitive resin composition containing an azide compound as a
photosensitive agent, as in the case of coating the substrate with a
composition containing an o-quinone diazide compound. The photosensitive
resin composition layer is procured, followed by irradiating the surface
of the resin composition layer with such an energy beam as described
previously through a desired mask pattern. In this stage, the azide
compound (22) given below, which is contained in the irradiated portion
(exposed portion) of the photosensitive resin composition layer, is
converted into a nitrene radical (23) by the light irradiation, as shown
below:
##STR21##
The nitrene radical (23) thus formed reacts with the hydroxyl group bonded
to the aromatic ring, which is introduced into a polyamic acid derivative
in the resin component of the exposed portion, performs a
hydrogen-withdrawing reaction and a crosslinking reaction with a double
bond of the resin component so as to crosslink the polymer chains of the
resin component.
In the next step, a baking treatment, i.e., post-exposure baking, is
applied to the photosensitive resin composition layer after the exposure
step at about 90.degree. to 200.degree. C. for about 5 seconds to 60
minutes. The post-exposure baking permits further strengthening the
crosslinkage of the polymer chains of the resin component in the exposed
portion, i.e., the crosslinkage formed by the function of the nitrene
radical (23) in the exposed portion.
After the post-exposure backing, a development is applied to the
photosensitive resin composition layer by means of a dipping method using
an alkaline aqueous solution, a spraying method, etc. as in the
development described previously. It should be noted that, in the
non-exposed portion of the photosensitive resin composition layer, the
hydroxyl group bonded to the aromatic ring remaining in the polyamic acid
derivative in the resin component reacts with the alkali metal ion or
ammonium ion present in the alkaline developing solution so as to form a
phenoxide and, thus, the resin composition is dissolved in the alkaline
developing solution.
In the exposed portion, however, the resin component is crosslinked as
described above, with the result that the molecular weight of the resin
component is increased and, thus, the resin composition is made insoluble
in the alkaline developing solution. It follows that the exposed portion
alone is selectively left unremoved after the development. In other words,
the photosensitive resin composition according to any of the first to
third embodiments of the present invention performs the function of a
negative photosensitive material, in which the exposed portion is rendered
insoluble in the developing solution in the exposure and developing steps
in the case where the composition contains an azide compound as a
photosensitive agent and a pattern formation is carried out by the process
described above.
In the case of using an azide compound as a photosensitive agent, it is
possible to omit the post-exposure baking as in the case of using an
o-quinone diazide compound described previously. However, it is desirable
to apply the post-exposure baking in order to improve the contrast of the
formed pattern and the adhesion between the resin composition film and the
semiconductor substrate.
Further, it is possible to apply a rinsing treatment with water, alcohol,
acetone, etc. after the development in order to remove the developing
solution residue, followed by applying a baking treatment or the like.
In the present invention, it is possible to form a thin polyamic acid film
on a substrate before formation of a passivation film or an interlayer
insulating film by using the photosensitive resin composition of the
present invention. In this case, a semiconductor substrate is coated first
with a polyamic acid, followed by heating and drying (baking) the coating
at about 90.degree. to 200.degree. C. for about 10 seconds to 60 minutes
so as to form a polyamic acid film having a thickness of about 0.1 to 100
microns, preferably about 0.2 to 50 microns. Then, the polyamic acid film
is further coated with a photosensitive resin composition of the present
invention in a thickness of about 0.5 to 100 microns, followed by heating
and drying (baking) the resin composition coating at 70.degree. to
170.degree. C. for about 10 seconds to 60 minutes so as to form a resin
composition layer. After formation of the resin composition layer, applied
is the pattern forming process such as the light-exposure and development
described above.
The polyamic acid film formed first on the substrate is not particularly
restricted, as far as the polyamic acid exhibits a satisfactory
heat-resistance and a high adhesion with the substrate. In general, used
is a polyamic acid prepared by the reaction between an acid anhydride and
a diamine. In order to improve the adhesion between the polyamic acid film
and the substrate, it is possible to use a polyamic acid copolymer having
a small amount of siloxane diamine units. It is also possible to add a
small amount of a silane coupling agent to the polyamic acid. Further, in
order to impart a flexibility to the main chain of the polyamic acid and
to improve the adhesion between the polyamic acid film and the substrate,
it is possible to use a polyamic acid having a benzophenone skeleton or
biphenyl skeleton in the acid component. It should be noted that a
polyamic acid film generally fails to exhibit a high adhesion with the
substrate, if the molecular weight of the polyamic acid is unduly small.
Thus, the polyamic acid used for forming a film on the substrate should
desirably have a molecular weight of at least 10,000.
Where a polyamic acid film is formed in advance on the substrate surface as
described above, it is possible to improve the adhesion between the resin
composition layer and the substrate. Even in this case, the photosensitive
resin composition of the present invention performs the function of a
positive or negative photosensitive material in the light-exposure and
developing steps depending on the chemical structure of the resin
component, the kind of the photosensitive agent used, and the pattern
forming process employed. Incidentally, the polyamic acid film formed
first on the substrate is developed simultaneously with the photosensitive
resin composition layer of the present invention in the developing step.
The pre-treatment described above for forming a polyamic acid film on a
substrate is also effective in the case of forming a polyimide film
pattern by using an alkali-soluble photosensitive polyimide described in
Published Unexamined Japanese Patent Application No. 64-630 referred to
previously. In this case, a polyamic acid thin film is formed first on a
semiconductor substrate, followed by forming a photosensitive polyimide
film on the polyamic acid film. Further, a exposure and development are
applied as desired to the photosensitive polyimide film so as to form a
desired pattern. It should be noted that the polyamic acid film formed
first on the substrate is developed in the developing step by an alkaline
developing solution simultaneously with the photosensitive polyimide film.
In the next step, the resultant pattern is heated so as to cure and obtain
a desired polyimide film pattern. It is important to note that the
pre-treatment noted above permits improving the adhesion between the
polyimide film pattern and the semiconductor substrate.
Table F shows examples of the photosensitive resin composition of the
present invention which are desirably used for the process of forming a
polyimide film pattern comprising the step of forming in advance a
polyamic acid film on a substrate surface.
The photosensitive resin composition according to any of the first to third
embodiments of the present invention performs the functions described
below regardless of the kind of the photosensitive agent used and the
process of forming a polyimide film pattern employed.
The photosensitive resin composition layer of a predetermined pattern after
the development is heated at a predetermined temperature. The heating
permits removing the substituent group introduced into the side chain of
the polyamic acid derivative having a repeating unit (1), the azide
compound serving to crosslink the polymer chains of the resin component,
the o-quinone diazide compound contained in the resin component, and the
like. The heating also permits evaporating the solvent component remaining
in the coated film. As a result, the polyamic acid is cyclized, thereby
forming a film pattern of polyimide having a repeating unit represented by
general formula (24) given below:
##STR22##
In the heating process, it is desirable to gradually elevate the
temperature from room temperature to the final heating temperature of
150.degree. to 450.degree. C. If the final heating temperature is lower
than 150.degree. C., the polyamic acid derivative partially fails to be
imidized in the polyimide forming step. If the polyamic acid derivative
partially remains unreacted, the thermal stability of the formed polyimide
film tends to be impaired. On the other hand, if the final heating
temperature exceeds 450.degree. C., the imidized polymer tends to be
decomposed, with the result that the thermal stability is impaired.
A resin encapsulated semiconductor device is manufactured by applying, for
example, an ordinary encapsulating process using an encapsulating resin
such as an epoxy resin to the semiconductor substrate having a polyimide
film pattern formed on the surface by using the photosensitive resin
composition according to any of the first to third embodiments of the
present invention.
Since the patterned polyimide film exhibits excellent electrical insulating
properties, a high resistance to radiation and an excellent heat
resistance, the patterned polyimide film acts as a satisfactory
passivation film or an interlayer insulating film in a semiconductor
device.
As described above, the photosensitive resin composition according to any
of the first to third embodiments of the present invention performs two
different functions, i.e., the function of a positive or negative
photosensitive material in the light-exposure and developing steps and the
function of a polyimide film used as a passivation film or interlayer
insulating film used in a semiconductor device. It follows that the use of
the photosensitive resin composition of the present invention makes it
possible to perform continuously the photoresist process for patterning a
polyimide film and the polyimide film forming process, which were
conventionally perfomed as two different processes, for the pattern
formation of a passivation film or an interlayer insulating film. Since it
is possible to form a polyimide film pattern without separately using a
photoresist, the composition of the present invention permits simplifying
the process of forming a polyimide film pattern.
The photosensitive resin composition of the present invention can also be
used as a photoresist for the ordinary fine processing for PEP. In this
case, the photosensitive resin composition layer is patterned on a
substrate by the process described previously, followed by selectively
etching the substrate by means of the ordinary dry etching or wet etching
process, with the patterned resin composition layer used as an etching
resistant mask.
It is also possible to form a pattern by using a known a precursor of a
polyimide other than the photosensitive resin composition of the present
invention by utilizing the baking treatment after the exposure step, i.e.
the post-exposure baking, which is employed as desired in the process of
forming a passivation film or an interlayer insulating film using the
photosensitive resin composition according to any of the first to third
embodiments of the present invention described above. In this case, a
photosensitive resin composition according to a fourth embodiment of the
present invention is prepared by mixing a resin component of a polyamic
acid having a repeating unit (2) given above and a photosensitive agent of
a naphthoquinone diazide compound. To be more specific, a resin layer
containing as a main component a resin composition of the fourth
embodiment is formed on a substrate, followed by selectively exposing the
resin layer to light and subsequently applying a baking treatment to the
resin layer at 130.degree. to 200.degree. C. Further, a development is
applied to the resin layer after the baking treatment, followed by heating
the developed resin layer after the development so as to imidize the
polyamic acid having a repeating unit (2) and, thus, to form a polyimide
film pattern.
In the photosensitive resin composition of the fourth embodiment, the
compounds similar to the polyamic acid contained in the resin component of
the composition according to the second embodiment of the present
invention can be used as the polyamic acid having a repeating unit (2).
On the other hand, the naphthoquinone diazide compounds used as the
photosensitive agent in the composition of the fourth embodiment are not
particularly restricted. It is possible to use in the fourth embodiments
the compounds similar to those used in the composition of any of the first
to third embodiments of the present invention. For example, it is possible
to use as the photosensitive agent 1,2-naphthoquinone diazide-4-sulfonic
acid, 1,2-naphthoquinone diazide-5-sulfonic acid, 2,1-naphthoquinone
diazide-4-sulfonic acid, 2,1-naphthoquinone diazide-5-sulfonic acid, and
derivatives thereof such as a salt, ester and amide thereof. It is
particularly desirable to use 1,2-naphthoquinone diazide-5-sulfonic acid
ester. Also, it is desirable to use the compounds QD-16 to QD-51 shown in
Table B referred to previously in conjunction with the photosensitive
resin compositions according to the first to third embodiments of the
present invention.
In the photosensitive resin composition according to the fourth embodiment
of the present invention, it is desirable to use the naphthoquinone
diazide compound in an amount of 5 to 70 parts by weight, preferably 25 to
45 parts by weight, based on 100 parts by weight of the polyamic acid
having a repeating unit represented by general formula (2). If the
naphthoquinone diazide compound is used in an excessively large amount,
the thickness of the resin layer is unduly diminished by the heating in
the imidizing step, with the result that the resolution of the formed
polyimide film pattern tends to be impaired. On the other hand, if the
amount of the naphthoquinone diazide compound is unduly small, the
photosensitivity of the resin layer in the light-exposing step is lowered,
with the result that the resolution of the formed polyimide film pattern
tends to be lowered. It should also be noted that, in the photosensitive
resin composition of the fourth embodiment, it is possible to add the
naphthoquinone diazide compound in the form of a solution prepared by
dissolving the compound in an organic solvent such as methylethyl ketone,
cyclohexane, acetate cellosolve, N,N-dimethylformamide,
N-methyl-2-pyrrolidone or hexamethylphosphoric triamide.
In the method of forming a polyimide film pattern described above, it is
possible to form either a positive or negative pattern by properly
selecting the kind of the naphthoquinone diazide compound contained as a
photosensitive agent in the photosensitive resin composition of the fourth
embodiment, the conditions of the post-exposure baking, etc. The reasons
for the particular function have not yet been clarified sufficiently. For
example, in the case of using 1,2-naphthoquinone diazide-4-sulfonic acid
ester as a photosensitive agent, chemical reactions are considered to take
place as described below.
Specifically, the photosensitive agent noted above is considered to undergo
the reactions shown below in the exposed portion and non-exposed portion
of the resin layer in the exposure and developing steps. In the exposed
portion of the photosensitive resin composition of the fourth embodiment,
1,2-naphthoquinone diazide-4-sulfonic acid ester (25) is converted into
indene carboxylic acid in the exposure step and, at the same time, is
decomposed into 1-sulfo-3-carboxylidene (26) and the skeletal portion,
i.e. the main chain portion of the polzamic acid, as shown in reaction
formula (a) given below:
##STR23##
where R' represents a monovalent organic group.
Further, reactions (b) to (d) given below are brought about in the exposed
portion in the step of the post-exposure baking, i.e., the baking
treatment after the exposure:
(b) 1-sulfo-3-carboxylidene formed in the exposure step serves to partially
imidize the polyamic acid having a repreating unit (2).
(c) The indene carboxylic acid is decarboxylated to convert into an indene
derivative.
(d) where the 1,2-naphthoquinone diazide-4-sulfonic acid ester used is
polyfunctional, the unreacted 1,2-naphthoquinone diazide-4-sulfonic acid
ester is crosslinked in the light-exposure step.
On the other hand, reactions (e) and (f) given below take place in the step
of the post-exposure baking in the non-exposed portion of the
photosensitive resin composition of the fourth embodiment:
(e) 1,2-naphthoquinone diazide-4-sulfonic acid ester is thermally
decomposed to convert into an indene carboxylic acid.
(f) Where the 1,2-naphthoquinone diazide-4-sulfonic acid ester used is
polyfunctional, the unreacted 1,2-naphthoquinone diazide-4-sulfonic acid
ester is crosslinked in the light-exposure step.
When it comes to the exposed portion of the photosensitive resin
composition of the fourth embodiment, the solubility in the alkaline
developing solution is promoted by reaction (a) given above. By the
contrary, the solubility in the alkakine developing solution is lowered by
reactions (b) to (d). On the other hand, the solubility of the non-exposed
portion in the alkaline developing solution is promoted by reaction (e).
By the contrary, the solubility in the alkaline developing solution is
lowered by reaction (f).
In the method of forming a polyimide film pattern described above, it is
considered reasonable to understand that a positive pattern is formed
finally where the contribution of reaction (a) is greater than that of
reactions (b) to (d), and a negative pattern is formed finally where the
contribution of reactions (b) to (d) is greater than that of reaction (a).
Which of reaction (a) or reactions (b) to (d) is more predominant in the
exposed portion of the photosensitive resin composition of the fourth
embodiment depends on the kind of the naphthoquinone diazide compound used
as the photosensitive agent, conditions of the light-exposure step, the
baking conditions after the exposure step, etc. It follows that it is
possible to form either a positive or negative pattern by suitably
selecting the various conditions in the method of forming a polyimide film
pattern described above.
In the case of using the photosensitive resin composition according to the
fourth embodiment of the present invention, it is possible to form a
polyimide film pattern by substantially the same method as in the case of
using the composition according to any of first to third embodiments of
the present invention. Specifically, a polyamic acid having a repeating
unit (2) and a naphthoquinone diazide compound are dissolved in a suitable
organic solvent, followed by removing fine impurity materials from the
resultant solution by means of, for example, filtering so as to prepare a
varnish of the photosensitive resin composition. Then, a substrate such as
a semiconductor substrate is coated with the varnish by means of, for
example, s rotary coating method or dipping method, followed by heating
and drying (baking) the coating so as to form a resin layer.
In the next step, the surface of the resin layer is selectively exposed
through a desired mask pattern to an energy beam such as an X-ray, visible
light, infrared radiation, ultraviolet radiation or an electron beam
(exposure step). It is possible to employ any of the contact type or
projection type exposure system. The resin layer after the exposure step
is subjected to a baking treatment at 130.degree. to 200.degree. C. using,
for example, a hot plate, followed by cooling the resin layer. If the
temperature for the baking treatment is unduly low, the resultant pattern
fails to exhibit a sufficiently high resolution. On the other hand, if the
temperature for the baking treatment is unduly high, the solubility of the
resin layer in the alkaline developing solution is lowered, making it
difficult to perform the subsequent development. The baking treatment
should preferably be carried out at a temperature falling within a range
of between 140.degree. and 160.degree. C. The baking treating time, which
depends on the baking temperature, should generally be about 0.5 to 60
minutes, preferably about 1 to 4 minutes. If the baking treating time is
unduly short, the resultant pattern fails to exhibit a sufficiently high
resolution. On the other hand, if the baking treating time is unduly long,
the subsequent development applied to the resin layer is made difficult.
After the baking treatment, a development is applied to the resin layer
using an alkaline aqueous solution. In this step, the exposed portion or
non-exposed portion of the resin layer is selectively dissolved in the
developing solution and, thus, removed so as to form a desired positive or
negative pattern. It is possible to use as the alkaline aqueous solution
the organic or inorganic alkaline solution used for developing a resin
layer of the photosensitive resin composition according to any of the
first to third embodiments of the present invention.
Further, the resin layer having a predetermined pattern, which has been
developed as described above, is heated at a predetermined temperature. As
a result, the polyamic acid having a repeating unit (2), which is
contained in the resin layer, is cyclized (imidized) so as to form a
polyimide film pattern having a repeating unit represented by general
formula (27) given below:
##STR24##
In the heating process, it is desirable to gradually elevate the
temperature from room temperature to the final heating temperature of
90.degree. to 400.degree. C. If the temperature is rapidly elevated in the
heating process, the polyamic acid partially fails to be imidized in the
polyimide forming process. If the polyamic acid partially remains
unreacted, the thermal stability tends to be impaired.
A resin encapsulated semiconductor device can be manufactured by applying
an ordinary encapsulating process using an encapsulating resin such as an
epoxy resin to the semiconductor substrate having a polyimide film pattern
formed on the surface by the particular method using a photosensitive
resin composition according to the fourth embodiment of the present
invention. Since the patterned polyimide film exhibits excellent
electrical insulating properties, a high resistance to radiation, and an
excellent heat resistance, the patterned film can suitably used as a
passivation film or an interlayer insulating film in the semiconductor
device.
Like the photosensitive resin composition according to any of the first to
third embodiments of the present invention, the composition of the fourth
embodiment can also be allowed to perform two different functions by
employing a suitable method, i.e., the function of a positive or negative
photosensitive material in the light-exposure and developing steps and the
function of a polyimide film acting as a passivation film or as an
interlayer insulating film. It follows that the method of forming a
polyimide film pattern using the photosensitive resin composition of the
fourth embodiment makes it possible to perform continuously the
photoresist process for the patterning a polyimide film and the polyimide
film forming process, which were conventionally performed as two different
processes. Since it is possible to form a polyimide film pattern without
separately using a photoresist, the composition of the present invention
permits simplifying the process of forming a polyimide film pattern.
Further, the polyimide film pattern formed by the particular method using
photosensitive resin composition according to the fourth embodiment of the
present invention can be used in the ordinary dry etching or wet etching
process as an etching resistant mask for the ordinary fine etching
treatment for PEP.
Let us describe Examples of the present invention in order to more clearly
set forth the technical idea of the present invention. Needless to say,
the technical scope of the present invention is not restricted by the
following Examples.
Examples 1-29 given below are directed to the photosensitive resin
compositions according to the first to third embodiments of the present
invention. The chemical structures of the compounds referred to by
abbreviations in these Examples and Tables 1-11 included in these Examples
are shown in Table G.
EXAMPLE 1
A four-necked flask having an inner volume of 100 ml purged with a nitrogen
gas was charged with 2.18 g (0.01 mol) of pyromellitic dianhydride (PMDA),
2.48 g (0.02 mol) of 3-hydroxybenzyl alcohol, and 10 ml of
N-methyl-2-pyrrolidone (NMP). The mixture was stirred at room temperature
for 24 hours so as to obtain dihydroxybenzyl pyromellitate.
Then, the temperature within the flask was lowered to 0.degree. C.,
followed by adding a solution prepared by dissolving 2.00 g (0.01 mol) of
4,4'-diaminodiphenylether (ODA) in 10 ml of NMP while stirring the system.
Further, a solution prepared by dissolving 4.53 g (0.022 mol) of
dicyclohexyl carbodimide (DCC) in NMP was dripped into the flask over 25
minutes.
The reaction solution thus obtained was maintained at 5.degree. C. for
carrying out reactions for 4 hours, followed by removing the formed
precipitate by filtration under a reduced pressure. The resultant filtrate
was put in 600 ml of water so as to obtain a precipitate of a polyamic
acid ester.
2.0 g of the polyamic acid ester was dissolved in 8 g of NMP, and 0.46 g of
1,2-naphthoquinone diazide-sulfonic acid ester of
2,3,4,4'-tetrahyroxybenzophenone (ester substitution number of 3) acting
as a photosensitive agent was added to the resultant solution. Then, the
resultant solution was passed through a filter having a pore size of 0.5
micron so as to obtain a photosensitive resin composition according to the
first embodiment of the present invention.
EXAMPLES 2-4
Photosensitive resin compositions according to the first embodiment of the
present invention were prepared by the method similar to that of Example 1
using the raw material compositions shown in Table 1 described below.
EXAMPLE 5
2.0 g of the polyamic acid ester prepared as in Example 1 was dissolved in
8 g of NMP, followed by adding 0.40 g of 2,6-di-(4'-azidebenzal)-4-methyl
cyclohexanone as a photosensitive agent to the resultant solution so as to
prepare a photosensitive resin composition according to the first
embodiment of the present invention (see Table 1).
Each of the photosensitive resin compositions of the first embodiment
prepared in Examples 1-5 was subjected to evaluation tests with respect to
various properties as follows:
Test 1: (Evaluation of Resolution Performance)
A silicon wafer was coated with the photosensitive resin composition by
means of rotary coating method using a spinner. The coating was then
heated and dried at 90.degree. C. for 5 minutes, followed by exposing the
dried film to light for 60 seconds through a patterning mask. An exposure
apparatus (PLA-500F manufactured by Canon Inc.) was used in the exposure
step. After the exposure, the silicon wafer was dipped for 90 seconds in
an alkaline developing solution, i.e., 2.38 wt % aqueous solution of
tetramethyl ammonium hydroxide (TMAH), for the developing purpose,
followed by rinsing with water so as to form a desired pattern.
A cross section of each of the patterns formed by using the photosensitive
resin compositions prepared in Examples 1-5 was observed by an electron
microscope (SEM). Table 2 shows the conditions of the test and the
results.
Test 1': (Evaluation of Resolution Performance)
A silicon wafer having a diameter of 3 inches was coated with the
photosensitive resin composition prepared in Example 1. The coating was
heated and dried for 10 minutes on a hot place of 90.degree. C. so as to
obtain a dried film having a thickness of 5 microns. Then, the film was
exposed to an ultraviolet radiation through a patterning mask using an
exposure apparatus PLA-500F noted previously. After the exposure, the
silicon wafer was subjected to a baking treatment for 10 minutes on a hot
plate of 150.degree. C., followed by dipping the silicon wafer for 90
seconds in an alkaline developing solution (2.38 wt % aqueous solution of
TMAH) for the developing purpose. Finally, the wafer was rinsed with water
so as to form a desired pattern.
A cross section of the pattern thus formed was observed with an electron
microscope (SEM). Table 2 shows the conditions and results of test 1'.
The results shown in Table 2 suggest that the polyimide film pattern formed
by using the photosensitive resin composition according to the first
embodiment of the present invention exhibits a resolution suitable for
using the polyimide film pattern as a passivation film or an interlayer
insulating film in a semiconductor device. Further, tests 1 and 1' suggest
that the baking treatment after the exposure step, i.e. the post-exposure
baking, is effective for improving the resolution of the formed pattern.
TABLE 1
__________________________________________________________________________
Polyamic acid derivative
(numerical denoting molar ratio)
Resin component
Photosensitive
Photosen-
a* (weight (g) of
agent
sitive resin
Tetracarboxilic polyamic acid
(weight (g) of
composition
dianhydride
b* Diamine derivative used)
comound used)
__________________________________________________________________________
Example 1
PMDA 3-hydroxybenzyl
ODA -- 2.0 g QD-4
1.0 alcohol 1.0 0.46 g
2.0
Example 2
PMDA 3-hydroxybenzyl
ODA 6FDA
2.0 g QD-4
1.0 alcohol 0.7 0.3 0.46 g
2.0
Example 3
PMDA 4-hydroxybenzyl
ODA 6FDA
2.0 g QD-4
1.0 alcohol 0.7 0.3 0.46 g
2.0
Example 4
BTDA 3-hydroxybenzyl
ODA 6FDA
2.0 g QD-4
1.0 alcohol 0.7 0.3 0.46 g
2.0
Example 5
PMDA 3-hydroxybenzyl
ODA -- 2.0 g QD-4
1.0 alcohol 1.0 0.40 g
2.0
__________________________________________________________________________
b*: Compound reacted with a*
Description in the specification should be referred to with respect to
abbreviations of compounds in the table.
TABLE 2
__________________________________________________________________________
Tests 1/1' (Resolution Performance)
d* Initial
Photosensitive Conc. of
Developing
e* film
resin Exposure
Exposure
developing
time Resolution
thickness
composition
apparatus
(mJ/cm.sup.2)
solution
(sec) (.mu.M)
(.mu.M)
__________________________________________________________________________
Example 1
PLA-500F
200 2.38% 60 1.0 P 5.0
Example 2
" 250 " " 5.0 P 4.8
Example 3
" 230 " " 2.5 P 5.0
Example 4
" 150 " " 2.0 P 2.0
Example 5
" 200 " " 10.0 N
5.0
Example 1
a* 200 " 90 8.0 N 5.0
PLA-500F
__________________________________________________________________________
a*: Baking treatment between exposure and developing steps (corresponding
to test 1')
d*: Developing solution, TMAH aqueous solution (wt %)
e*: P . . . Positive pattern, N . . . Negative pattern
EXAMPLE 6
A four-necked flask having an inner volume of 500 ml purged with a nitrogen
gas was charged with 10.91 g (0.05 mol) of PMDA and 60 ml of NMP, which
was cooled to 0.degree. C. Then, a solution prepared by dissolving 10.01 g
(0.05 mol) of ODA in 40 ml of NMP was slowly put into the flask. The
resultant reaction solution was stirred for 5 hours while maintaining the
reaction solution at 0.degree. to 5.degree. C. so as to obtain a polyamic
acid solution. Further, added to the polyamic acid solution were a
solution prepared by dissolving 10.91 g (0.1 mol) of 4-aminophenol in 100
ml of NMP and another solution prepared by dessolving 20.63 g (0.1 mol) of
DCC in 40 ml of NMP. The resultant reaction solution was kept stirred for
4 hours at room temperature. Then, 10 ml ethanol was added to the reaction
solution. The resultant solution was kept stirred for 2 hours, followed by
removing the insoluble components by means of filtration. The filtrate was
dripped into 3 liters of methanol so as to precipitate polymer. The
precipitated polymer was separated by means of filtration and, then, dried
so as to obtain a polyamic acid derivative.
2 g of the polyamic acid derivative and 0.5 g of 1,2-naphthoquinone
diazide-4-sulfonic acid ester of 2,3,4,4'-tetrahydroxy benzophenone (ester
substitution number of 3) were dissolved in 10 g of NMP, followed by
filtration with a filter having a pore size of 0.5 micron so as to obtain
a photosensitive resin composition according to the first embodiment of
the present invention.
EXAMPLE 7
2 g of the polyamic acid derivative prepared as in Example 6 and 0.2 of
2,6-di-(4'azidebenzal)-4-methyl cyclohexane acting as a photosensitive
agent were dissolved in 10 g of NMP, followed by filtration with a filter
having a pore size of 0.5 micron so as to obtain a photosensitive resin
composition according to the first embodiment of the present invention.
Test 2 (Evaluation of Resolution Performance)
A silicon wafer having a diameter of 3 inches was coated with the
photosensitive resin composition prepared in each of Examples 6 and 7 by
the rotary coating method using a spinner. Then, the coating was heated
and dried for 5 minutes on a hot plate of 100.degree. C. The dried film
was exposed to light through a patterning mask using a PLA-500F noted
previously as an exposure apparatus. After the exposure, the silicon wafer
was dipped for 120 seconds in an alkaline developing solution (2.38 wt %
aqueous solution of TMAH) for the developing purpose, followed by rinsing
with water so as to form a desired pattern.
A cross section of each of the patterns thus formed using the
photosensitive resin compositions prepared in Examples 6 and 7 was
observed with an electron microscope. A pattern having resolution of 20
microns with an exposure of 350 mJ/cm.sup.2 was recognized with respect to
the photosensitive resin composition prepared in Example 6. Likewise, a
pattern having are solution of 50 microns with an exposure of of 400
mJ/cm.sup.2 was recognized with respect to the photosensitive resin
composition prepared in Example 7.
Test 3: (Evaluation of Adhesion with Phosphosilicate Glass Film)
A silicon wafer covered with a phosphosilicate glass film (PSG film) was
coated with the photosensitive resin composition prepared in each of
Examples 6 and 7 by the spin coating method. Then, a silicon chip having a
PSG film, 2 mm square, formed on the surface was put on the coated film
such that the PSG film of the silicon chip is in direct contact with the
coated film so as to form a laminate structure of PSG film/photosensitive
resin composition layer/PSG film. The laminate structure was dried at
90.degree. C. for 30 minutes, followed by applying a baking treatment at
150.degree. C. for 30 minutes, at 250.degree. C. for 1 hour and, then, at
350.degree. C. for 30 minutes, so as to form a polymer film having the
thickness controlled at about 5 microns between the silicon wafer and the
silicon chip. The resultant sample was left to stand for 100 hours within
a pressure cooker under steam of 120.degree. C. and 2.2 atms. The shear
breaking strength of the silicon chip, 2 mm square, put on the silicon
wafer was measured with respect to each of the sample subjected to the
pressure cooker treatment (PCT) and a control sample not subjected to the
PCT.
The shear breaking strength was found to be 2.2 kg/mm.sup.2 at 0 hour of
PCT (not subjecting to the PCT) and 1.8 kg/mm.sup.2 at about 100 hours of
PCT in the sample formed by using the photosensitive resin composition of
Example 6. On the other hand, the shear breaking strength was found to be
2.1 kg/mm.sup.2 at 0 hour of PCT and 1.6 kg/mm.sup.2 at about 100 hours of
PCT in the sample formed by using the photosensitive resin composition of
Example 7.
EXAMPLE 8
A four-necked flask having an inner volume of 500 ml purged with a nitrogen
gas was charged with 21.8 g (0.1 mol) of PMDA, 24.8 g (0.2 mol) of
3-hydroxybenzyl alcohol, and 100 ml of NMP. The mixture was stirred at
room temperature for 24 hours so as to obtain dihydrobenzyl pyromellitate.
Then, the flask was cooled to 0.degree. C., followed by pouring a solution
prepared by dissolving 20.0 g (0.1 mol) of ODA in 100 ml of NMP into the
flask while stirring the solution within the flask. Further, a solution
prepared by dissolving 45.3 g (0.22 mol) DCC in NMP was dripped into the
flask over 25 minutes. The resultant reaction solution was maintained at
5.degree. C. so as to carry out the reaction for 4 hours, followed by
removing the formed precipitate by means of filtration under a reduced
pressure. Then, the filtrate was put in liters of methanol so as to form
precipitate. The resultant precipitate was recovered by means of
filtration and, then, dried at 80.degree. C. for 14 hours within a vacuum
dryer so as to obtain 47 g of a polyamic acid ester.
On the other hand, a four-necked flask having an inner volume of 100 ml
purged with a nitrogen gas was charged with 2.18 g (0.01 mol) of PMDA and
10 ml of NMP, followed by dripping a solution prepared by dissolving 2 g
of ODA in 10 ml of NMP to the mixed solution while stirring the mixed
solution. The resultant reaction solution was maintained at 5.degree. C.
so as to carry out reaction for 10 hours and, thus, to obtain a polyamic
acid solution.
Added to the polyamic acid solution were 16.72 g of the polyamic acid ester
prepared in advance as described above, 105 g of NMP, and 5.26 g of a
photosensitive agent, i.e., 1,2-naphthoquinone diazide-5-sulfonic acid
ester of 2,3,4,4'-tetrahydroxy benzophenone (average esterification rate
of 75%). The mixture was stirred for 3 hours and, then, the resultant
solution was filtered with a filter having a pore size of 0.5 micron so as
to prepare a photosensitive resin composition according to the second
embodiment of the present invention.
EXAMPLES 9-17
Photosensitive resin compositions according to the second embodiment of the
present invention were prepared as in Example 8 by using polyamic acid
derivatives, polyamic acids and photosensitive agents, which were prepared
by mixing the raw materials in the mixing ratio shown in Table 3 described
below.
Various properties of the photosensitive resin compositions of the second
embodiment were evaluated as follows:
Test 4: (Evaluation of Resolution Performance)
The resolution of some of the photosensitive resin compositions prepared in
Examples 8-17 were evaluated as in test 1 conducted in Examples 1-5. Table
4 shows the evaluating conditions and the results of the evaluation.
Test 5: (Evaluation of Adhesion with PSG Film)
A silicon wafer covered with a PSG film was coated with the photosensitive
resin composition prepared in each of Examples 10, 14 and 15 by means of
the spin coating method. Then, a silicon chip having a PSG film, 2 mm
square, formed on the surface was put on the coated film such that the PSG
film of the silicon chip is in direct contact with the coated film so as
to form a laminate structure of PSG film/photosensitive resin composition
layer/PSG film. The laminate structure was dried at 90.degree. C. for 30
minutes, followed by applying a baking treatment at 150.degree. C. for 30
minutes, at 250.degree. C. for 1 hour and, then, at 350.degree. C. for 30
minutes, so as to form a polymer film having the thickness controlled at
about 5 microns between the silicon wafer and the silicon chip. The
resultant sample was left to stand for 100 hours within a pressure cooker
under steam of 120.degree. C. and 2.2 atms. The shear breaking strength of
the silicon chip, 2 mm square, put on the silicon wafer was measured with
respect to each of the sample subjected to the pressure cooker treatment
(PCT) and a control sample not subjected to the PCT. Table 5 shows the
results.
Test 6: (Evaluation of Adhesion with Epoxy Resin for Encapslating
Semiconductor
A silicon wafer covered with a PSG film was coated with the photosensitive
resin composition prepared in each of Examples 10, 14 and 15 by means of
the spin coating method. Then, the sample was dried at 90.degree. C. for
30 minutes, followed by applying a heat treatment at 150.degree. C. for 30
minutes, at 250.degree. C. for 1 hour and, then, at 350.degree. C. for 30
minutes, so as to form a polymer film having the thickness controlled at
about 5 microns. Further, a silicon wafer having a polymer film formed on
the surface was diced into small pieces each sized at 10 mm.times.30 mm,
followed by forming an encapsulating resin film, 3 mm square, on each of
the diced samples by using a low pressure transfer molding machine. An
epoxy resin for encapsulating a semiconductor device (KE-300Ts
manufactured by Toshiba Chemical K.K.) was used as the encapsulating
resin, and the transfer molding was performed for 3 minutes at a
temperature of 175.degree. C. and a pressure of 80 kg/cm.sup.2. The
resultant sample was left to stand for 100 hours within a pressure cooker
under steam of 120.degree. C. and 2.2 atms. A shear breaking strength of
the encapsulating resin was measured for each of the sample subjected to
the pressure cooker treatment (PCT) and a control sample not subjected to
the PCT. Table 5 shows the results.
The results shown in Tables 4 and 5 suggest that the polyimide film pattern
formed by using the photosensitive resin composition according to the
second embodiment of the present invention exhibits a resolution and
adhesion suitable for using the patterned film as a passivation film or an
interlayer insulating film in a semiconductor device.
TABLE 3
__________________________________________________________________________
Photo-
c* sensitive
Polyamic acid derivative Resin agent
(numeral denoting molar ratio) component
(weight
Polyamic acid
a* (weight
(g) of
(numeral denoting molar
ratio)
Ex-
Tetracar- (g) of
com- Tetracar-
am-
boxilic compound
pound
boxilic
ple
dianlydride
b* Diamine used) used)
dianlydride
Diamine
__________________________________________________________________________
8 PMDA
-- 3-hydroxy-
ODA -- -- 16.72 g/
QD-4 PMDA
-- ODA --
1.0 benzyl-
1.0 4.18 g
5.22 g
1.0 1.0
alcohol 2.0
9 BTDA
-- 4-hydroxy-
ODA -- -- 8 g/2 g
QD-4 BTDA
-- ODA --
1.0 benzyl
1.0 2.5 g
1.0 1.0
alcohol 2.0
10 BTDA
PMDA
4-hydroxy-
ODA TSL9306
-- 8 g/2 g
QD-4 BTDA
PMDA
ODA TSL9306
0.75
0.25
benzyl
0.95 0.05 2.5 g
0.75
0.25
0.95 0.05
alcohol 2.0
11 PMDA
-- 3-hydroxy-
ODA -- -- 5 g/5 g
QD-1 BTDA
PMDA
ODA TSL9306
1.0 benzyl
1.0 3.0 g
0.75
0.25
0.95 0.05
alcohol 2.0
12 PMDA
-- 4-hydroxy-
ODA -- -- 5 g/5 g
QD-2 PMDA
-- ODA --
1.0 benzyl
1.0 2.5 g
1.0 1.0
alcohol 2.0
13 DSDA
-- 4-amino-
BAPB ODA -- 6 g/4 g
QD-4 PMDA
-- ODA --
1.0 phenyl 2.0
0.5 0.5 2.5 g
1.0 1.0
14 PMDA
BTDA
4-hydroxy-
ODA 6FDA TSL9306
6 g/4 g
QD-9 BTDA
PMDA
ODA TSL9306
0.5 0.5 benzyl
0.25 0.70 0.05 3.0 g
0.75
0.25
0.95 0.05
alcohol 2.0
15 BTDA
PMDA
4-hydroxy-
HFBAPP
ODA TSL9306
7 g/3 g
DA-1 BTDA
PMDA
HFBAPP
ODA
0.75
0.25
benzyl
0.50 0.45 0.05 2.5 g
0.75
0.25
0.50 0.50
alcohol 2.0
16 BTDA
PMDA
4-amino-
BAPP ODA -- 8 g/2 g
A-19 BTDA
PMDA
BAPP ODA
0.50
0.50
phenyl 2.0
0.50 0.50 2.5 g
0.50
0.50
0.50 0.50
17 PMDA
-- 3-amino-
BAPP ODA -- 8 g/2 g
A-27 PMDA
-- BAPP ODA
1.0 phenyl 2.0
0.50 0.50 2.5 g
1.0 -- 0.50 0.50
__________________________________________________________________________
b*: Compound reacted with a*
c*: Weight (g) of the polyamic acid derivative/weight (g) of the polymic
acid (solid)
Description in the specification should be referred to with respect to
abbreviations of compounds in the table.
TABLE 4
__________________________________________________________________________
Tests 4 (Resolution Performance)
d* Initial
Photosensitive Conc. of
Developing
e* film
resin Exposure
Exposure
developing
time Resolution
thickness
Composition
apparatus
(mJ/cm.sup.2)
solution
(sec) (.mu.m)
(.mu.m)
__________________________________________________________________________
Example 8
PLA-500F
250 2.38% 90 5.0 P 5.0
Example 9
" 300 " 120 5.0 P 4.0
Example 10
" 280 " 90 5.0 P 3.8
" g-line 320 " 90 6.0 P 5.0
stepper
(NA 0.45)
Example 13
PLA-500F
250 1.19% 60 10.0 P
4.5
Example 15
KrF Excimer
120 2.38% 60 1.0 N 1.0
Laser
Stepper
(NA 0.37)
Example 17
KrF Excimer
120 2.38% 60 1.0 N 1.0
Laser
Stepper
(NA 0.37)
__________________________________________________________________________
d*: Developing solution, TMAH aqueous solution (wt %)
e*: P . . . Positive pattern, N . . . Negative pattern
TABLE 5
______________________________________
Test 6 f*
Test 5 f* (Adhesion with
(Adhesion with Encapsulating
Photosensitive
PSG film resin)
resin PCT PCT PCT PCT
composition
0 hour 100 hours 0 hour 100 hours
______________________________________
Example 10 2.2 1.5 4.3 3.5
Example 14 2.0 1.2 3.5 2.8
Example 15 2.3 1.4 3.7 2.5
______________________________________
f*: unit (kg/mm.sup.2)
EXAMPLE 18
16.11 g of BTDA and 12.41 g of m-hydroxybenzyl alcohol were dissolved in
dimethylacetoamide (DMAC), and reaction was carried out for 3 hours at
100.degree. C. under a nitrogen gas atmosphere so as to obtain benzyl
alcohol ester. Then, a solution prepared by dissolving 9.51 g of ODA and
0.62 g of bis-(.gamma.-aminopropyl)tetramethyldisiloxane in 30 ml of DMAC
was added to the reaction mixture. Further, a solution prepared by
dissolving 20.83 g of dicyclohexylcarbodiimide in 30 ml of DMAC was added
to the reaction mixture while cooling the solution with ice. After
completion of the dropping, the reaction mixture was stirred for 1 hour
while cooling the reaction mixture with ice, followed by further stirring
the reaction mixture at room temperature for 10 hours. After the stirring,
5 ml of ethanol was added to the reaction mixture, followed by stirring
the resultant solution for 2 hours and subsequently removing the insoluble
components from filtration. The resultant filtrate was poured into 2
liters of methanol so as to permit the formed polymer to re-precipitate.
The precipitated polymer was separated by means of filtration and, then,
dried so as to obtain 20.4 g of a polyamic acid ester (PE-1), the yield
being 55%.
On the other hand, a four-necked flask having an inner volume of 500 ml
purged with a nitrogen gas was charged with 3,3',4,4'-benzophenone
tetracarboxylic dianhydride and 100 ml of NMP, which was cooled with ice.
Then, a solution prepared by dissolving 19.02 g of ODA and 1.24 g of bis
(.gamma.-aminoropyl)tetramethyldisiloxane in 120 ml of NMP was slowly
added to the mixed solution while stirring the reaction solution such that
the temperature of the reaction solution should not exceed 10.degree. C.
The reaction solution was kept stirred continuously for 10 hours while
maintaining the temperature to fall within a range of between 0.degree. C.
and 5.degree. C. so as to obtain a polyamic acid solution (PA-1).
Further, a solution was prepared by mixing 0.4 g of polyamic acid ester
(PE-1), 8.56 g of polyamic acid solution (PA-1), 0.67 g of
o-naphthoquinone diazide (QD-5) and 4 g of NMP and, then, filtered with a
filter having a pore size of 0.5 micron so as to obtain a photosensitive
resin composition according to the second embodiment of the present
invention.
EXAMPLE 19
21.8 g of PMDA was suspended in 200 g of ethanol, and the suspension was
stirred under a nitrogen gas atmosphere for 12 hours under heating at
70.degree. C. The resultant reaction solution was poured into 500 ml of
water, and the precipitated crystals were separated out by means of
filtration. Then, the separated crystals were recrystallized within a
mixed solvent of ethanol/water so as to obtain 12 g of pyromellitic acid
ester.
In the next step, a solution prepared by dissolving 9.30 g (0.03 mol) of
the pyromellitic acid ester, 7.09 g of 4,4'-diaminodiphenylether and 0.37
g of bis(.gamma.-aminopropyl)tetramethyldisiloxane in 100 ml of NMP. The
resultant solution was cooled with ice, followed by adding to the
resultant solution another solution prepared by dissolving 6.30 g of
dicyclohexylcarbodiimide in 20 g of NMP. After completion of the addition,
the solution was stirred at room temperature for 12 hours, followed by
adding 5 ml of ethanol to the solution. The resultant solution was further
stirred for 2 hours, followed by removing the insoluble components by
means of filtration. The resultant filtrate was poured into 2 liters of
water so as to permit precipitation of a polymer. The polymer thus
precipitated was recovered by means of filtration and, then, dried so as
to obtain 11 g of a polyamic acid ester (PE-2) with a yield of 55%.
2 g of the polyamic acid ester (PE-2) thus prepared was mixed with 2 g of
the polyamic acid ester (PE-1) prepared in Example 18, 5.35 g of polyamic
acid solution (PA-1), the polymer content of which was 1 g, 1.25 g of
o-naphthoquinone diazide (QD-5), and 6 g of NMP, and the resultant
solution was filtered with a filter having a pore size of 0.5 micron so as
to prepare a photosensitive resin composition according to the second
embodiment of the present invention.
Various properties of the photosensitive resin composition of the second
embodiment thus prepared were evaluated as follows:
Test 7: (Evaluation of Sensitivity)
A silicon wafer having a diameter of 3 inches was coated with the
photosensitive resin composition prepared in Example 18 by the spin
coating method. Then, the wafer was heated on a hot plate of 110.degree.
C. for 3 minutes so as to form a resin composition film having a thickness
of 2.1 microns. The resin composition film was exposed to light emitted
from a mercury lamp through a quartz mask for measuring the sensitivity,
i.e., a quartz mask having 15 sections differing from each other in the
transmittance over a range of between 1% and 75%. After the exposure, the
wafer was subjected to a baking treatment for 1 minute on a hot plate of
110.degree. C., followed by dipping the wafer in an alkaline developing
solution (2.38 wt % aqueous solution of TMAH) for 3 minutes for the
developing purpose so as to obtain a positive pattern.
FIG. 1 is a graph showing the sensitivity of the photosensitive resin
composition obtained in the test. The amount of light exposure is plotted
on the abscissa A of FIG. 1, with the ordinate B denoting the
film-remaining rate in the exposed portion, i.e., the ratio in the
thickness of the film after the development to the thickness of he film
before the development in the exposed portion.
Test 8: Evaluation of Resolution Performance)
A silicon wafer having a diameter of 3 inches was coated with each of the
photosensitive resin compositions prepared in Examples 18 and 19 by means
of the rotary coating method using a spinner, followed by heating and
drying the wafer on a hot plate so as to dry the coated film. Then, the
coated film was exposed to light for 60 seconds through a patterning mask
using an exposure apparatus of PLA-500F noted previously. After the
exposure, the film formed of the photosensitive resin composition prepared
in Example 19 was subjected to a baking treatment by putting the wafer on
a hot plate. Then, the silicon wafer was dipped in an alkaline developing
solution (aqueous solution of TMAH) for the developing purpose, followed
by rinsing the wafer with water.
A cross section of each of the patterns thus formed was observed with an
electron microscope. Table 6 shows the conditions and results of the test.
The results shown in Table 6 indicate that the polyimide film pattern
formed by using the photosensitive resin composition according to the
second embodiment of the present invention exhibits a resolution suitable
for using the pattern as a passivation film or an interlayer insulating
film in a semiconductor device.
Test 9: (Evaluation of Resolution Performance)
A silicon wafer was coated with the polyamic acid solution (PA-1), followed
by heating the wafer on a hot plate of 150.degree. C. for 20 seconds so as
to form a film having a thickness of 1.0 micron. The film thus formed was
further coated with the photosensitive resin composition obtained in
Example 18, followed by heating the wafer on a hot plate of 110.degree. C.
for 3 minutes for the drying purpose so as to form a resin composition
film having a thickness of 5 microns. Then, the resin composition film was
exposed to light through a patterning mask, followed by baking the film
for 1 minute on a hot plate of 110.degree. C. Further, the silicon wafer
was dipped in an alkaline developing solution (2.38 wt % aqueous solution
of TMAH) for 2 minutes for the developing purpose, followed by rinsing the
wafer with water.
A cross section of the pattern thus formed was observed with an electron
microscope. Recognized was resolution of a positive pattern having lines
and spaces of 5 microns (see item J* in Table 6).
In this test, a polyamic acid thin film was formed first on a substrate by
using a photosensitive resin composition according to the second
embodiment of the present invention, followed by forming a pattern by
using a photosensitive resin composition of the present invention. Even in
this case, the resultant polyimide film pattern exhibits a resolution
suitable for using the pattern as a passivation film or an interlayer
insulating film in a semiconductor device, as apparent from the result of
the test.
Test 10: (Evaluation of Adhesion with PSG Film)
The adhesion strength of the polyimide film pattern, which was formed by
using each of the photosensitive resin compositions prepared in Examples
18 and 19, with a PSG film was evaluated by the method and under
conditions similar to those in test 5. With respect to the photosensitive
resin composition prepared in Example 18, the evaluation of the adhesion
strength with a PSG film also covered the case where the substrate was
coated in advance with a polyamic acid. Table 7 shows the results of the
evaluation.
Test 11: (Evaluation of Adhesion with Semiconductor Encapsulating Epoxy
Resin)
The adhesion strength of a polyimide film pattern with an epoxy resin for
encapsulating a semiconductor device was evaluated by the method and under
conditions similar to those in test 6 with respect to each of the
photosensitive resin compositions prepared in Examples 18 and 19. With
respect to the photosensitive resin composition prepared in Example 18,
the evaluation also covered the case where the substrate was coated in
advance with a polyamic acid. Table 7 also shows the results of the
evaluation.
The results shown in Table 7 suggest that the polyimide film pattern formed
by using a photosensitive resin composition according to the second
embodiment of the present invention exhibits a high adhesion suitable for
using the polyimide film pattern as a passivation film or an interlayer
insulating film in a semiconductor device. It is also shown that, when it
comes to the photosensitive resin composition prepared in Example 18, it
is desirable to coat the substrate with a polyamic acid before formation
of a photosensitive resin composition layer so as to improve the adhesion
of the resultant polyimide film pattern with the substrate or with the
epoxy resin for encapsulating a semiconductor device.
TABLE 6
__________________________________________________________________________
Tests 8/9 (Resolution Performance)
d* Initial
Photosensitive Conc. of
Developing
e* film
resin Exposure
Exposure
developing
time Resolution
thickness
Composition
apparatus
(mJ/cm.sup.2)
solution
(sec) (.mu.m)
(.mu.m)
__________________________________________________________________________
Example 18
i* PLA-500F
180 2.38% 100 5.0 P 5.0
j* PLA-500F
220 " 120 5.0 P 5.0
Example 19
k* PLA-500F
200 " 180 10.0 N
3.0
l* PLA-500F
180 " 120 10.0 P
5.0
__________________________________________________________________________
d*: Developing solution, TMAH aqueous solution (wt %)
e*: P . . . positive pattern, N . . . negative pattern
i*: Drying after coating at 110.degree. C. for 3 minutes (corresponding t
test 8)
j*: Drying after coating at 110.degree. C. for 3 minutes (corresponding t
test 9)
k*: Drying after coating at 90.degree. C. for 5 minutes, baking after
light exposure at 160.degree. C. for 2 minutes (corresponding to test 8)
1*: Drying after coating at 90.degree. C. for 10 minutes, baking after
light exposure at 150.degree. C. for 1 minute (corresponding to test 8)
TABLE 7
______________________________________
Test 11 f*
Test 10 f* (Adhesion with
(Adhesion with Encapsulating
Photosensitive
PSG film resin)
resin PCT PCT PCT PCT
composition
0 hour 100 hours 0 hour 100 hours
______________________________________
Example 18 g* 2.6 1.3 3.3 2.0
h* 2.8 1.5 3.5 2.3
Example 19 g* 2.3 1.2 3.3 2.1
______________________________________
f*: unit (kg/mm.sup.2)
g*: Substrate was directly coated with photosensitive resin composition
h*: Substrate was coated first with polyamic acid and, then, with
photosensitive resin composition
Comparative Example
A four-necked flask purged with a nitrogen gas was charged with 20.0 g of
PMDA, 20.6 g of potassium-t-butoxide and 200 ml of tetrahydrofuran (THF),
and the system was stirred for 12 hours. Then, the formed precipitate was
separated out by means of filtration, followed by washing with THF and
diethylether and subsequently drying the washed precipitate. The dried
precipitate was dissolved in 200 ml of water, neutralized with a dilute
sulfuric acid and, then, the formed precipitate was separated out by means
of filtration. Further, the separated precipitate was washed with water
and, then, dried. Still further, the dried precipitate was recrystallized
within a mixture of ethanol and water so as to obtain 15 g of pyromellitic
acid ester.
In the next step, 11.98 g of the pyromellitic acid ester noted above, 6.01
g of ODA, and 8.4 g of triethylamine were dissolved in 50 ml of NMP, and
the solution was cooled to -10.degree. C. in a three-necked blask purged
with a nitrogen gas. Further,
N,N'-(phenylphosphino)bis[2(3H)-benzothizolon] was slowly added to the
solution, followed by adding 100 ml of NMP to the solution. The resultant
solution was stirred for 2 hours. After the stirring, the solution was
slowly poured to 2 liters of methanol which was kept vigorously stirred so
as to precipitate a polymer, which was separated out by filtration and,
then, dried under vacuum so as to obtain 10.5 g of polyamic acid ester.
1 g of the polyamic acid ester thus prepared was mixed with 5.35 g of the
polyamic acid solution (PA-1) prepared in Example 18, 3 g of NMP and 0.5 g
of o-naphthoquinone diazide (QD-5) acting as a photosensitive agent so as
to prepare a solution. The solution was passed through a filter having a
pore size of 0.5 micron so as to prepare a photosensitive resin
composition for Comparative Example 1. On the other hand, another solution
was prepared by mixing 8.02 g of the polyamic acid solution (PA-1), the
polymer content of which was 1.5 g, 0.5 g of the polyamic acid ester
prepared in Comparative Example 1, 0.86 g of o-naphthoquinone diazide
(QD-5) acting as a photosensitive agent, and 2 g of NMP. The solution was
passed through a filter having a pore size of 0.5 micron so as to prepare
a photosensitive resin composition for Comparative Example 2.
It should be noted that, in the photosensitive resin composition in each of
Comparative Examples 1 and 2, an organic group having at least one
hydroxyl group bonded to the aromatic ring is not introduced into the side
chain of the polyamic acid derivative, i.e., the resin component of the
composition.
The coating, light exposure and development with an alkaline developing
solution (1.19 wt % aqueous solution of TMAH) were performed as in test 8
described previously, except for the post-exposure baking, with respect to
the photosensitive resin composition for each of the Comparative Examples
1 and 2. The exposed portion and non-exposed portion of the resin
composition layer were both dissolved in the alkaline developing solution,
resulting in failure to form a pattern. This is considered to suggest
that, in the photosensitive resin composition of the present invention,
the post-exposure baking is required for the pattern formation in the case
where an organic group having at least one hydroxyl group bonded to the
aromatic ring is not introduced into the side chain of the resin component
of the composition.
Incidentally, the composition according to each of Comparative Examples 1
and 2 was treated as in test 8 including the post-exposure baking.
Resolution of lines and spaces each having a width of 5.0 microns was
recognized in this case. This suggests that, even if an organic group
having at least one hydroxyl group attached to the aromatic ring is not
introduced into the side chain of the resin component of a photosensitive
resin composition, the post-exposure baking permits the composition to
form a pattern.
EXAMPLE 20
A four-necked flask having an inner volume of 100 ml purged with a nitrogen
gas was charged with 1.526 g (0.007 mol) of PMDA, 1.763 g (0.014 mol) of
3-hydroxybenzyl alcohol and 10 ml of NMP. The mixed solution was stirred
at room temperature for 24 hours so as to obtain dihydroxybenzyl
pyromellitate.
Then, the flask was cooled to 0.degree. C., followed by adding a solution
prepared by dissolving 2.00 g (0.01 mol) of 4,4'-diaminodiphenylether in
10 ml of NMP to the flask while stirring the flask. Further, a solution
prepared by dissolving 3.17 g (0.0154 mol) of DCC in NMP was dripped into
the reaction flask over 25 minutes. The resultant reaction solution was
maintained at 5.degree. C. so as to carry out the reaction for 4 hours,
followed by slowly adding 0.654 g (0.003 mol) of PMDA to the reaction
solution. Further, the reaction solution was maintained at 5.degree. C. so
as to carry out the reaction for 4 hours, followed by removing the formed
precipitate by filtration under a reduced pressure. The filtrate was
poured into 600 ml of water so as to precipitate a polyamic acid ester
having a copolymer structure.
2 g of the polyamic acid ester thus prepared was dissolved in 8 g of NMP,
followed by adding to the solution 0.46 g of a photosensitive agent, i.e.,
1,2-naphthoquinone diazide-5-sulfonic acid ester of 2,3,4,4'-tetrahydroxy
benzophenone (QD-4, average esterification rate of 75%) so as to prepare a
photosensitive resin composition according to the third embodiment of the
present invention.
EXAMPLES 21 TO 24
Photosensitive resin compositions according to the third embodiment of the
present invention were prepared as in Example 20 using the raw material
compositions shown in Table 8.
EXAMPLE 25
2.0 g of a polyamic acid ester prepared as in Example 20 was dissolved in 8
g of NMP, followed by adding as a photosensitive agent 0.40 g of
2,6-di-(4'-azidebenzal)-4-methylcyclohexane (A-21) to the solution so as
to prepare a photosensitive resin composition according to the third
embodiment of the present invention (see Table 8).
EXAMPLE 26
A reaction flask was charged with 16.11 g (0.05 mol) of BTDA, 12.41 g of
3-hydroxylbenzyl alcohol, and 100 g of NMP. The mixture, which was kept
stirred slowly, was heated to 90.degree. C. and the stirring was continued
for additional 3 hours at 90.degree. C. Then, the reaction solution was
cooled to room temperature, followed by slowly adding a solution prepared
by dissolving 15.02 g (0.075 mol) of 4,4'-diaminodiphenylenter in 70 g of
NMP to the reaction solution. Then, the reaction solution was maintained
at 10.degree. C., and a solution prepared by dissolving 21.66 g (0.105
mol) of dicyclohexylcarbodiimide in 50 g of NMP was dripped into the
reaction solution over 30 minutes. The resultant reaction solution was
stirred for 4 hours at 10.degree. C.
In the next step, 5.45 g (0.025 mol) of PMDA was added to the reaction
solution, and the resultant solution was kept stirred for 5 hours at a
reaction temperature of 10.degree. C. Then, a by-product precipitate was
removed by means of suction filtration so as to obtain a mother liquor,
i.e., a solution of a polyamic acid derivative having a copolymer
structure. Further, 1.0 g of o-naphthoquinone diazide (QD-5) was dissolved
in 20 g of the polyamic acid derivative solution, and the resultant
solution was passed through a filter having a pore size of 0.5 micron so
as to prepare a photosensitive resin composition according to the third
embodiment of the present invention (see Table 8).
Various properties of the photosensitive resin composition of the third
embodiment thus prepared were evaluated as follows:
Test 12: (Evaluation of Resolution Performance)
The resolution of the photosensitive resin composition prepared in each of
Examples 20 to 26 was evaluated by the method similar to that in test 1.
Table 9 shows the conditions and results of the evaluation.
Test 12': (Evaluation of Resolution Performance)
A silicon wafer having a diameter of 3 inches was coated with the
photosensitive resin composition prepared in Example 26 and, then, put on
a hot plate of 90.degree. C. for heating and drying the coating for 10
minutes, so as to obtain a composition film having a thickness of 4
microns. The composition film was exposed to an ultraviolet radiation with
an exposure of 200 mJ/cm.sup.2 through a patterning mask by using an
exposure apparatus PLA-500F referred to previously. After the exposure,
the silicon wafer was baked for 20 minutes on a hot plate of 140.degree.
C., followed by dipping the silicon wafer in an alkaline developing
solution (2.38 wt % aqueous solution of TMAH) for 7 minutes at room
temperature for the developing purpose. Finally, the wafer was rinsed with
water.
A cross section of each of the patterns thus formed was observed with an
electron microscope. The conditions and results of the evaluation are
shown in Table 9. The results shown in Table 9 suggest that the polyimide
film pattern formed by using the photosensitive resin composition of the
third embodiment exhibits a resolution suitable for using the pattern as a
passivation film or an interlayer insulating film in a semiconductor
device.
TABLE 8
__________________________________________________________________________
Polyamic acid derivative
(numerical denoting molar ratio) Resin component
Photosensitive
Photosen-
a* a* (weight (g) of
agent
sitive resin
Tetracarboxylic Additional
polyamic acid
(weight (g) of
composition
dianhydride
b* Diamine Reactnat
derivative used)
comound used)
__________________________________________________________________________
Example 20
PMDA 3-hydroxybenzyl
ODA -- PMDA 2.0 g QD-4
0.7 alcohol 1.4
1.0 0.3 0.46 g
Example 21
PMDA 3-hydroxybenzyl
ODA 6FDA
PMDA 2.0 g QD 4
0.7 alcohol 1.4
0.7 0.3 0.3 0.46 g
Example 22
PMDA 4-hydroxybenzyl
ODA 6FDA
PMDA 2.0 g QD-4
0.7 alcohol 1.4
0.7 0.3 0.3 0.46 g
Example 23
BTDA 3-hydroxybenzyl
ODA -- BTDA 2.0 g QD-4
0.8 alcohol 1.6
1.0 0.2 0.46 g
Example 24
PMDA 3-hydroxybenzyl
ODA -- BTDA 2.0 g QD-4
0.7 alcohol 1.4
1.0 0.3 0.46 g
Example 25
PMDA 3-hydroxybenzyl
ODA -- PMDA 2.0 g A-21
0.7 alcohol 1.4
1.0 0.3 0.40 g
Example 26
BTDA 3-hydroxybenzyl
ODA -- PMDA 20 g QD 5
0.5 alcohol 1.0
0.75 0.25 0.1 g
__________________________________________________________________________
b*: Compound reacted with a*
Description in the specification should be referred to with respect to
abbreviations of compounds in the table.
TABLE 9
__________________________________________________________________________
Tests 12/12' (Resolution Performance)
d* Initial
Photosensitive Conc. of
Developing
e* film
resin Exposure
Exposure
developing
time Resolution
thickness
composition
apparatus
(mJ/cm.sup.2)
solution
(sec) (.mu.M)
(.mu.M)
__________________________________________________________________________
Example 20
PLA-500F
400 2.38% 20 10.0 P
8.0
Example 21
" 350 " " 8.0 P 5.0
Example 22
" 280 " " 5.0 P 5.5
Example 23
" 200 " " 4.0 P 3.0
Example 24
" 290 " " 5.0 N 5.0
Example 25
" 350 " " 5.0 N 5.0
Example 26
m* 180 " 420 6.0 N 4.0
PLA-500F
__________________________________________________________________________
a*: Developing solution, TMAH aqueous solution (wt %)
d*: P . . . positive pattern, N . . . negative pattern
e*: Baking treatment between exposure at 140.degree. C. for 20 minutes
(corresponding to test 12')
EXAMPLE 27
Polyamic acid (PA-2) having an intrinsic viscosity of 0.60 g/dl was
obtained by the reaction among 0.1 mol of BTDA, 0.095 mol of ODA and 0.005
mol of bis(.gamma.-aminopropyl)tetramethylsiloxane. Then, a solution was
prepared by dissolving 7.5 g of a polyamic acid derivative represented by
formula (PE-3) given below, 2.5 g of the polyamic acid (PA-2) noted above,
and 2.5 g of a photosensitive agent, i.e., o-naphthoquinone diazide
compound (QD-4) in 50 g of NMP:
##STR25##
The solution thus prepared was passed through a filter having a pore size
of 0.5 micron so as to obtain a photosensitive resin composition according
to the second embodiment of the present invention.
EXAMPLES 28 AND 29
Photosensitive resin compositions of the present invention were prepared as
in Example 27 by using the resin components and the photosensitive agents
shown in Table 10.
Test 13: (Evaluation of Resolution Performance)
A silicon wafer was coated with a polyamic acid solution (CT4200T
manufactured by Toshiba Chemical Co., Ltd.). Then, the wafer was heated on
a hot plate of 160.degree. C. for 20 minutes so as to obtain a coated film
having a thickness of 0.4 micron. The coated film was further coated with
the photosensitive resin composition prepared in Example 27, and the wafer
was heated on a hot plate of 90.degree. C. for 10 minutes so as to obtain
a composition film having a thickness of 5 microns. Then, the composition
film was exposed to light with an exposure apparatus of 200 mJ/cm.sup.2
through a patterning mask, followed by dipping the wafer in an alkaline
developing solution (2.38 wt % aqueous solution of TMAH) for the
developing purpose. Finally, the wafer was rinsed with water so as to form
a desired pattern.
A cross section of the pattern thus formed was observed with an electron
microscope.
A similar test was applied with respect to each of the photosensitive resin
compositions prepared in Examples 28 and 29 so as to evaluate the
resolution of the formed pattern.
Table 10 also shows the conditions and results of the test.
Test 14: (Evaluation of Adhesion)
A silicon wafer was coated with a polyamic acid solution available on the
market, followed by heating the wafer so as to form a film. The film thus
formed was further coated with the photosensitive resin composition
prepared in Example 27, as in test 13 described above. Further, the wafer
was heated within an oven at 150.degree. C. for 30 minutes, at 250.degree.
C. for 30 minutes and, then, at 350.degree. C. for 30 minutes so as to
form a cured film. The cured film was imparted with cutting lines with a
razor at an interval of 1 mm so as to form 100 square sections each sized
at 1 mm.times.1 mm.
A cellophane tape, which was attached to the cured film, was peeled off
(cross cut test). However, the cured film was not peeled off at all. Then,
the wafer was exposed to a saturated steam of 12.degree. C. (pressure
cooker test, PCT). The cross cut test was applied again to the wafer 100
hours after the pressure cooker test, with the result that peeling of the
film was not recognized at all.
Test 15: (Evaluation of Adhesion with PSG Film)
A silicon wafer having a PSG film formed on the surface was coated first
with a polyamic acid and, then, with the photosensitive resin composition
prepared in each of Examples 27 to 29. Then, a silicon chip, 2 mm square,
having a PSG film formed on the surface and a polyamic acid thin film
formed on the PSG film was put on the photosensitive resin composition
layer so as to form a laminate structure of PSG film/polyamic acid thin
film/photosensitive resin composition layer/polyamic acid thin film/PSG
film.
The adhesion strength of the photosensitive region composition with a PSG
film was evaluated by the method and under the conditions similar to those
in test 5. Table 11 shows the results.
Test 16: (Evaluation of Adhesion with Epoxy Resin for Encapsulating
Semiconductor Device)
A silicon wafer having a phosphosilicate glass (PSG) film formed on the
surface was coated first with a polyamic acid and, then, with the
photosensitive resin composition prepared in each of Examples 27 to 29.
The adhesion strength with an epoxy resin for encapsulating a semiconductor
device was evaluated by the method and under the conditions similar to
those in test 6. Table 11 also shows the results.
Tables 10, 11 and the result of test 14 collectively indicate that, where a
polyamic acid thin film is formed first on a substrate, followed by
forming a pattern by using the photosensitive resin composition of the
present invention, the resultant polyimide film pattern exhibits a
resolution and adhesion, etc. suitable for using the pattern as a
passivation film or an interlayer insulating film in a semiconductor
device.
TABLE 10
__________________________________________________________________________
Test 13 (resolution performance)
Polyamic acid
Film
coated in advance
thickness
Photosensitive resin
on substrate
after e*
composition Film coating d* Resolu-
Resin component/ thickness
of upper
Exposure
Develop-
tion
photosensitive agent
Polymer
(.mu.m)
layer
(mJ/cm.sup.2)
ment (.mu.m)
__________________________________________________________________________
Example 27
PE-3, PA-2/QD-4 =
CT4200T
0.4 5.0 200 2.38% TMAH
5.0 P
75:25 (weight ratio) 60 sec.
Example 27
PE-3, PA-2/QD-4 =
PA-2 30 40 350 1.19% TMAH
50.0 P
75:25 (weight ratio) 120 sec.
Example 28
PE-3/QD-5 PA-2 0.5 6.5 330 2.38% TMAH
5.0 P
60 sec.
Example 29
PE-1, PA-2 = 50:50
PA-2 0.3 3.0 220 1.19% TMAH
10.0 N
(weight ratio)/A-21 40 sec.
__________________________________________________________________________
d*: Developing solution, TMAH aqueous solution (wt %)
e*: P . . . Positive pattern, N . . . Negative pattern
Description in the specification should be referred to with respect to
abbreviations of compounds in the table.
TABLE 11
__________________________________________________________________________
Polyamic acid
Film Test 16 f*
Photo-
coated in advance
thickness
Test 15 f*
(Adhesion
sensitive
on substrate
after (Adhesion
with Encapsulating
resin Film coating
with PSG film
resin)
composi- thickness
of upper
PCT-
PCT- PCT- PCT-
tion Polymer
(.mu.m)
layer(.mu.m)
0 hour
100 hours
0 hour
100 hours
__________________________________________________________________________
Example 27
PA-2 30 40 3.2 1.8 4.0 2.9
Example 28
" 0.5 6.5 3.0 1.5 2.7 1.9
Example 29
" 0.3 3.0 3.2 1.7 4.1 3.0
__________________________________________________________________________
f*: unit kg/mm.sup.2
Description in the specification should be referred to with respect to
abbreviations of compounds in the table.
Reference Example
8.0 g of polyimide (PI-3) shown below and 2 g of o-naphthoquinone diazide
compound (QD-4) acting as a photosensitive agent were dissolved in 40 g of
NMP, followed by passing the resultant solution through a filter having a
pore size of 0.5 micron so as to prepare a photosensitive polyimide resin
composition:
##STR26##
Then, a silicon wafer was coated with a polyamic acid solution available on
the market, i.e., CT4200T referred to previously, followed by drying the
coating in an oven of 150.degree. C. for 1 hour so as to form a coated
film having a thickness of 0.8 micron. The coated film thus prepared was
further coated with the photosensitive polyimide resin composition film
noted above, followed by heating and drying on a hot plate for 5 minutes
so as to obtain a resin composition film having a thickness of 5.0 micron.
Then, the resin composition film was exposed to light through a patterning
mask, followed by dipping the wafer in an alkaline developing solution
(1.19% aqueous solution of TMAH) for the developing purpose. Finally, the
wafer was rinsed with water so as to obtain a positive pattern. The
pattern thus formed was observed with a microscope. Recognized was a
resolution of lines and spaces of 4 microns.
The photosensitive polyimide resin composition was subjected to tests for
evaluation of the adhesion strength with a phosphosilicate glass as in
test 15 and for evaluation of the adhesion strength with an epoxy resin
for encapsulating a semiconductor device as in test 16. The results
obtained in these tests were not better than those in the case of using
the photosensitive resin composition of the present invention.
The test results suggest that, where the substrate is coated in advance
with a polyamic acid solution, it is possible to form a satisfactory
polyimide film pattern in the cases of using various photosensitive
compositions including those which do not fall within the technical scope
of the present invention.
As described above, the photosensitive resin composition according to any
of the first to third embodiments of the present invention permits forming
a polyimide film pattern without using a photoresist, making it possible
to simplify the process of forming a polyimide film pattern in the
manufacture of a semiconductor device. What should also be noted is that
the polyimide film pattern formed by using the composition of the present
invention exhibits a resolution, adhesion, etc. suitable for using the
pattern as a passivation film or an interlayer insulating film in a
semiconductor device.
The Examples which follow are directed to the specific method of forming a
polyimide film pattern using a photosensitive resin composition according
to the fourth embodiment of the present invention. The abbreviations used
in Examples 30 to 61 and Tables 12 to 19, which follow, are explained in
Table G and H.
EXAMPLE 30
A nitrogen gas dried with phosphorus pentoxide was introduced in a reaction
flask equipped with a stirrer, a thermometer and a dropping funnel. Then,
the reaction flask was charged with 4.635 g (0.21 mol) of pyromellitic
dianhydride, 19.993 g (0.062 mol) of 3,3',4,4'-benzophenone
tetracarboxylic dianhydride, 0.333 g (0.003 mol) of maleic anhydride and
100 g of N-methyl-2-pyrrolidone. The resultant mixture was fully stirred
and, then, cooled to -5.degree. C.
Then, a solution prepared by dissolving 15.996 g (0.081 mol) of
4,4'-diaminodiphenylether and 1.199 g (0.003 mol) of
bis(.gamma.-aminopropyl)tetramethyldisiloxane in 69 g of
N-methyl-2-pyrrolidone was slowly dripped into the reaction flask. The
mixed solution thus prepared was maintained at a temperature falling
within a range of between -5.degree. and 0.degree. C. for 4 hours and,
then, reaction was carried out at room temperature (20.degree. C.) for 4
hours so as to obtain a polyamic acid. The mixed solution of the polyamic
acid thus prepared and N-methyl-2-pyrrolidone was controlled and a
logarithmic viscosity of the mixed solution was measured at 30.degree. C.,
the result being 0.83 dl/g.
In the next step, 10 g of the polyamic acid solution was mixed with 2.5 g
of a naphthoquinone diazide compound of the general formula given below,
and the mixture was sufficiently stirred at room temperature (20.degree.
C.) to form a homogeneous system:
##STR27##
The homogeneous mixture was passed through a membrane filter having a pore
size of 0.5 micron so as to obtain a photosensitive resin composition
containing as main components a polyamic acid and a naphthoquinone diazide
compound. A polyimide film pattern was formed by the particular pattern
forming method of the present invention by using the photosensitive resin
composition thus prepared, and various properties of the polyimide film
pattern were measured as follows:
Test 17: (Evaluation of Resolution Performance)
A silicon wafer having a diameter of 3 inches was coated with the
photosensitive resin composition prepared in Example 30 by using a
spinner, followed by heating the wafer on a hot plate of 100.degree. C.
for 10 minutes so as to form a resin layer having a thickness of 6.2
microns. The resin layer thus formed was exposed to light through a quartz
mask for resolution performance test by using a contact exposure machine
(CA-800 manufactured by Cobilt, Inc.), with a exposure of 70 mJ/cm.sup.2
(wavelength of 365 nm). After the exposure step, a baking treatment was
applied to the resin layer at 150.degree. C. for 2 minutes, followed by
dipping the wafer in a resist developing solution (2.38 wt % aqueous
solution of tetramethyl ammonium hydroxide) for 60 seconds and
subsequently applying water wash for 20 seconds so as to form a negative
pattern.
A cross section of the pattern thus formed was observed with an electron
microscope. Recognized was a resolution of lines and spaces of 3 microns.
The resultant pattern was heated at 320.degree. C. so as to form a
satisfactory polyimide film pattern.
Test 18: (Evaluation of Adhesion with Silicon Wafer)
A silicon wafer having a diameter of 3 inches was coated with the
photosensitive resin composition prepared in Example 30 by using a
spinner. The wafer was heated on a hot plate of 90.degree. C. for 10
minutes so as to form a resin layer having a thickness of 5.0 microns.
Then, the wafer was put in a constant temperature dryer and heated at
150.degree. C. for 1 hour, 250.degree. C. for 1 hour and, then, at
320.degree. C. for 1 hour, so as to imidize the resin layer formed on the
wafer. Further, the wafer was heated at 120.degree. C. for 24 hours under
a saturated steam of 2 atms, followed by evaluating the adhesion strength
by the checkers test method. It has been found that the resin layer did
not peel at all from the wafer, indicating a high adhesion strength of the
resin layer with the wafer.
Test 19: (Evaluation of Heat Resistance)
A silicon wafer having a diameter of 3 inches was coated with the
photosensitive resin composition prepared in Example 30 by using a
spinner. The wafer was heated on a hot plate of 90.degree. C. for 10
minutes so as to form a resin layer having a thickness of 5.0 microns.
Then, the wafer was put in a constant temperature dryer and heated at
150.degree. C. for 1 hour, 250.degree. C. for 1 hour and, then, at
320.degree. C. for 1 hour, so as to imidize the resin layer formed on the
wafer. After the heating, the resin layer was peeled off the wafer with a
razor, followed by subjecting the peeled resin layer to a
thermogravimetric analysis (TGA). Weight reduction caused by thermal
decomposition was not recognized until about 400.degree. C.
Comparative Tests for Evaluating Properties:
A silicon wafer having a diameter of 3 inches was coated with the
photosensitive resin composition prepared in Example 30 by using a
spinner. The wafer was heated on a hot plate of 90.degree. C. for 10
minutes so as to form a resin layer having a thickness of 5.0 microns.
Then, the resin layer thus formed was exposed to light through a quartz
mask for resolution performance test by using a contact exposure machine
CA-800 referred to previously, with a light exposure rate of 70
mJ/cm.sup.2 (wavelength of 365 nm). After the exposure step, the silicon
wafer was immediately dipped in a resist developing solution (2.38 wt %
aqueous solution of tetramethyl ammonium hydroxide) for 60 seconds so as
to form a pattern. Then, the silicon wafer was pulled out of the
developing solution and washed with water for 20 seconds. In this case,
however, the remaining portion of the patterned resin layer was found
dissolved, resulting in failure to form a good pattern.
On the other hand, a silicon wafer having a diameter of 3 inches was coated
with the photosensitive resin composition prepared in Example 30 by using
a spinner. The wafer was heated on a hot plate of 90.degree. C. for 10
minutes so as to form a resin layer having a thickness of 5.0 microns.
Then, the resin layer thus formed was subjected to a heat treatment at
150.degree. C. for 2 minutes, followed by exposing the resin layer to
light through a quartz mask for evaluating the resolution by using a
contact exposure machine CA-800 referred to previously, with a light
exposure of 70 mJ/cm.sup.2 (wavelength of 365 nm). Immediately after the
exposure step, the silicon wafer was dipped in a resist developing
solution (2.38 wt % aqueous solution of tetramethyl ammonium hydroxide)
for 60 seconds, resulting in failure to form a pattern. The pattern
formation is considered to have been achieved because the naphthoquinone
diazide compound contained in the resin layer was decomposed during the
heat treatment before the exposure step.
EXAMPLES 31 TO 38
Polyamic acid solutions were prepared as in Example 30 using the raw
material compositions shown in Table 12. Table 12 also shows the
logarithmic viscosity of each of the polyamic acid solutions prepared in
Examples 31 to 38. Further, photosensitive resin compositions of Examples
31 to 38 were prepared by mixing predetermined amounts of the polyamic
acid solutions and the naphthoquinone diazide compounds as shown in Table
12.
Test 20: Evaluation of Resolution Performance
A layer of the photosensitive resin composition prepared in each of
Examples 31 to 38, which was formed on a silicon wafer, was subjected to
light exposure, baking treatment, and development by the method and under
the conditions as in test 17 for evaluation of the resolution performance
for Example 30 so as to form a pattern. A cross section of each of the
patterns thus formed was observed with an electron microscope so as to
measure the resolution. Table 13 shows the results.
Test 21: (Evaluation of Adhesion with Silicon Wafer)
The adhesion strength between a formed pattern and a silicon wafer was
measured by the method and under the conditions as in test 18 for
evaluating the adhesion strength for Example 30 with respect to the
photosensitive resin composition prepared in each of Examples 31 to 38.
Table 13 also shows the results.
Test 22: (Evaluation of Heat Resistance)
The heat resistance of a pattern formed on a silicon wafer was measured by
the method and under the conditions as in test 19 for evaluating the heat
resistance for Example 30 with respect to the photosensitive resin
composition prepared in each of Examples 31 to 38. Table 13 also shows the
results.
As shown in Table 13, a negative pattern was formed in the case of using
the photosensitive resin composition prepared in any of Examples 31 to 38.
Particularly, the pattern formed by using the composition prepared in any
of Examples 31 to 36 was excellent in resolution, exhibited a high
adhesion between the formed pattern and the substrate, was sufficiently
high in the resistance to heat. When it comes to the composition prepared
in Example 37, in which a large amount of naphthoquinone diazide compound
was used, the weight reduction of the resin layer in the imidizing step
was large, and the adhesion strength of the resultant polyimide film with
the substrate was lowered. On the other hand, in the case of the
composition prepared in Example 38, in which the amount of naphthoquinone
diazide compound used was small, the resolution of the formed pattern was
somewhat low because each of the exposed portion and the non-exposed
portion was relatively high in solubility in an alkaline solution. Of
course, Example 38 was found inferior to the other Examples in the
patterning characteristics.
TABLE 12
__________________________________________________________________________
Examples
30 31 32 33 34 35 36 37 38
__________________________________________________________________________
Mixing of
Polyamic Acid
Tetracarboxylic
BPDA -- 17.653
-- 5.884
-- -- -- -- --
dianhydride
BTDA 19.993
12.888
17.721
18.688
11.921
15.788
22.554
19.993
19.933
(g) PMDA 4.635
-- 9.815
4.362
13.086
10.905
6.107
4.635
4.635
DPE 15.969
-- 19.219
18.819
-- 10.010
18.819
15.996
15.996
Diamine (g)
DAM -- 18.439
-- -- 19.232
8.922
-- -- --
ASi-a 1.119
0.944
-- 1.491
0.746
-- -- 1.119
1.119
ASi-b -- -- 1.089
-- -- 2.178
3.267
-- --
Monoamine (g)
.ANG. -- 0.559
-- -- -- -- -- -- --
T -- -- 0.428
-- -- -- -- -- --
Dicarboxylic
.ANG.-a
-- -- -- 0.592
-- -- -- -- --
anhydride
.ANG.-b
-- -- -- -- 0.924
-- -- -- --
.ANG.-c
-- -- -- -- -- 0.356
-- -- --
.ANG.-d
-- -- -- -- -- -- 0.672
-- --
.ANG.-e
0.333
-- -- -- -- -- -- 0.333
0.333
Synthetic
Temp. (.degree.C.)
-5.about.20
-5.about.25
-10.about.25
0.about.25
0.about.25
0.about.25
0.about.25
-5.about.20
-5.about.20
Conditions
Time (hour)
8 8 8 7 7 7 7 8 8
Logarithmic 0.82 0.82 0.79 0.58
0.92
0.79
0.61
0.82 0.82
Viscosity (dl/g)
Mixing Amount of
7.5 7.0 7.5 7.0 8.0 7.0 7.0 5.5 9.5
Polyamic Acid (g)
Mixing Amount of
PAC-a 2.5 3.0 -- -- -- -- -- -- --
Naphthoquinone
PAC-b -- -- 2.5 3.0 2.0 3.0 3.0 4.5 0.5
diazide compound
(g)
__________________________________________________________________________
TABLE 13
__________________________________________________________________________
Examples
30 31 32 33 34 35 36 37 38
__________________________________________________________________________
Coated Film Thickness
6.2 4.9 6.6 5.5 4.2 5.2 5.5 5.0
4.8
(.mu.m)
Test 20 3.0 2.5 2.0 1.5 2.5 2.0 1.5 10.0
25.0
(resolution/.mu.m)
(nega-
(nega-
(nega-
(nega-
(nega-
(nega-
(nega-
(nega-
(nega-
tive)
tive)
tive)
tive)
tive)
tive)
tive)
tive)
tove)
Test 21 0/100
0/100
0/100
0/100
0/100
0/100
0/100
50/100
0/100
(Adhesion
Evaluation by
Checker's test)
Test 22 420 430 410 430 425 425 430 350 430
(10% weight reduction
temperature)
__________________________________________________________________________
*Evaluation by Checker's test (Evaluation of Adhesion): Adhesion strentgh
with silicon wafer after heating for 24 hours under saturated steam of 2
atms.
*10% Weight Reduction Temperature (.degree.C.) (Evaluation of Heat
Resistance): TGA measurement after thermal curing at 320.degree. C.
EXAMPLES 39 TO 45
Polyamic acid solutions used in Examples 39 to 45 were prepared as in
Example 30 by using the raw material compositions shown in Table 14. Table
14 also shows the logarithmic viscosity of each of the polyamic acid
solutions noted above. Further, photosensitive resin compositions for
Examples 39 to 45 were prepared by mixing predetermined amounts of the
polyamic acid solutions with naphthoquinone diazide compound as shown in
Table 14.
Test 23: (Evaluation of Resolution Performance)
A layer of the photosensitive resin composition prepared in each of
Examples 39 to 45, which was formed on a silicon wafer, was subjected to
light exposure, baking treatment, and development by the method and under
the conditions as in test 17 for evaluation of the resolution performance
for Example 30 so as to form a pattern. In this test, the exposure was set
at 150 mJ/cm.sup.2, and the development was performed by dipping the
silicon wafer in an aqueous solution containing 1.19% by weight of
tetramethyl ammonium hydroxide, followed by washing the wafer with water.
A cross section of each of the patterns thus formed was observed with an
electron microscope so as to measure the resolution. Table 15 shows the
results.
Test 24: (Evaluation of Adhesion with Silicon Wafer)
The adhesion strength between a formed pattern and a silicon wafer was
measured by the method and under the conditions as in test 18 for
evaluating the adhesion for Example 30 with respect to the photosensitive
resin composition prepared in each of Examples 39 to 45. Table 15 also
shows the results.
Test 25: (Evaluation of Heat Resistance)
The heat resistance of a pattern formed on a silicon wafer was measured by
the method and under the conditions as in test 19 for evaluating the heat
resistance for Example 30 with respect to the photosensitive resin
composition prepared in each of Examples 39 to 45. Table 15 also shows the
results.
As shown in Table 15, a negative or positive fine pattern was formed in the
case of using the photosensitive resin composition prepared in any of
Examples 39 to 45. The pattern formed by using the composition prepared in
any of Examples 39 to 45 exhibited a high adhesion between the formed
pattern and the substrate, and was sufficiently high in the resistance to
heat.
When it comes to the composition prepared in each of Examples 39 to 44, the
formed pattern was found to exhibit a very high adhesion strength with the
silicon wafer in the test for evaluating the adhesion strength with the
silicon wafer. Specifically, even after heating for 62 hours at
120.degree. C., the formed pattern did not peel at all off the wafer. On
the other hand, peeling did not occur at all after heating for 24 hours at
120.degree. C. in the case of the composition prepared in Example 45.
However, the formed pattern was found to peel 10% off the wafer after the
heating for 62 hours. It is considered reasonable to understand that, in
the case of using a polyfunctional naphthoquinone diazide sulfonic acid
ester as a photosensitive agent as in Example 45, the unreacted
naphthoquinone diazide sulfonic acid ester is crosslinked during the heat
treatment so as to lower the flexibility of the resin layer. In the case
of using a monofunctional naphthoquinone diazide sulfonic acid ester as a
photosensitive agent as in Examples 39 to 44, however, the crosslinking
noted above does not take place, leading to an excellent adhesion strength
of the formed pattern with the wafer, as noted above.
Comparative Test for Evaluating Characteristics
A resin layer was formed on a silicon wafer by using the photosensitive
resin composition prepared in Example 39, followed by applying light
exposure to the resin layer as in test 23 described above. Immediately
after the light exposure, the silicon wafer was dipped in a resist
developing solution (1.19 wt % aqueous solution of tetramethyl ammonium
hydroxide). It was possible to form a pattern. However, when the wafer was
taken out of the developing solution and, then, washed with water for 30
seconds, the remaining portion of the resin layer was dissolved, resulting
in failure to form a satisfactory pattern.
TABLE 14
__________________________________________________________________________
Examples
39 40 41 42 43 44 45
__________________________________________________________________________
Mixing of
Polyamic Acid
Tetracarboxylic
BPDA -- 17.653
-- -- -- -- --
dianhydride
BTDA 19.993
12.888
17.721
11.921
15.788
22.554
19.993
(g) PWDA 4.635
-- 9.815
13.086
10.905
6.107
4.635
DPE 15.969
-- 19.219
-- 10.010
18.819
15.996
Diamine (g)
DAM -- 18.439
-- 19.232
8.922
-- --
ASi-a 1.119
0.944
-- 0.746
-- -- 1.119
ASi-b -- -- 1.089
-- 2.178
3.267
--
Monoamine (g)
.ANG. -- 0.559
-- -- -- -- --
T -- -- 0.428
-- -- -- --
Dicarboxylic
.ANG.-a
-- -- -- -- -- -- --
anhydride
.ANG.-b
-- -- -- 0.924
-- -- --
.ANG.-c
-- -- -- -- 0.356
-- --
.ANG.-d
-- -- -- -- -- 0.672
--
.ANG.-e
0.333
-- -- -- -- -- 0.333
Synthetic
Temp. (.degree.C.)
-5.about.20
-5.about.25
-10.about.25
0.about.25
0.about.25
0.about.25
-5.about.25
Conditions
Time (hour)
8 8 8 7 7 7 8
Logarithmic 0.82 0.82 0.79 0.92
0.79
0.61
0.82
Viscosity (dl/g)
Mixing Amount of
7.0 7.0 7.5 7.5 7.0 7.0 7.0
Polyamic Acid (g)
Mixing Amount of
PAC-c 3.0 -- -- 2.5 -- 3.0 --
Naphthoquinone
PAC-d -- 3.0 -- -- -- -- --
diazide compound
PAC-e -- -- 2.5 -- -- -- --
(g) PAC-f -- -- -- -- 3.0 -- --
PAC-g -- -- -- -- -- -- 3.0
__________________________________________________________________________
TABLE 15
__________________________________________________________________________
Examples
39 40 41 42 43 44 45
__________________________________________________________________________
Coated Film Thickness
4.5 4.0 5.0 4.0 3.7 5.1 4.5
(.mu.m)
Test 23 3.5 2.0 2.2 3.0 1.5 3.5 2.0
(resolution/.mu.m)
(posi-
(nega-
(nega-
(posi-
(nega-
(posi-
(nega-
tive)
tive)
tive)
tive)
tive)
tive)
tive
Test 24 0/100
0/100
0/100
0/100
0/100
0/100
10/100
(Adhesion;
Evaluation by
Checker's test)
Test 25 415 440 400 415 415 420 400
(10% weight redutcion
temperaure)
__________________________________________________________________________
*Evaluation by Checker's test (Evaluation of Adhesion): Adhesion strength
with silicon wafer after heating for 62 hours under saturated steam of 2
atms.
*10% Weight Reduction Temperature (.degree.C.) (Evaluation of Heat
Resistance): TGA measurement after thermal curing at 320.degree. C.
EXAMPLES 46 TO 52
Polyamic acid solutions used in Examples 46 to 52 were prepared as in
Example 30 by using the raw material compositions in Table 16. Table 16
also shows the logarithmic viscosity of each of the polyamic acid
solutions thus prepared. Then, photosensitive resin compositions for
Examples 46 to 52 were prepared by mixing predetermined amounts of the
polyamic acid solutions thus prepared and naphthoquinone diazide compound
as shown in Table 16.
Test 26: (Evaluation of Resolution Performance)
A layer of the photosensitive resin composition prepared in each of
Examples 46 to 52, which was formed on a silicon wafer, was subjected to
light exposure, baking treatment, and development by the method and under
the conditions as in test 17 for evaluation of the resolution performance
for Example 30 so as to form a pattern. In this test, the exposure was set
at 170 mJ/cm.sup.2, and the development was performed by dipping the
silicon wafer in an aqueous solution containing 1.19% by weight of
tetramethyl ammonium hydroxide, followed by washing the wafer with water.
A cross section of each of the patterns thus formed was observed with an
electron microscope so as to measure the resolution. Table 17 shows the
results.
Test 27: (Evaluation of Adhesion with Silicon Wafer)
The adhesion strength between a formed pattern and a silicon wafer was
measured by the method and under the conditions as in test 18 for
evaluating the adhesion strength for Example 30 with respect to the
photosensitive resin composition prepared in each of Examples 46 to 52.
Table 17 also shows the results.
Test 28: (Evaluation of Heat Resistance)
The heat resistance of a pattern formed on a silicon wafer was measured by
the method and under the conditions as in test 19 for evaluating the heat
resistance for Example 30 with respect to the photosensitive resin
composition prepared in each of Examples 46 to 52. Table 17 also shows the
results.
As shown in Table 17, a negative fine pattern was formed in the case of
forming a pattern by the method described above by using the
photosensitive resin composition prepared in any of Examples 46 to 52. The
pattern thus formed exhibited a high adhesion strength between the formed
pattern and the substrate, and was sufficiently high in the resistance to
heat.
In Examples 45 to 52, a polyfunctional naphthoquinone diazide sulfonic acid
ester was used as a photosensitive agent. However, the formed pattern was
found to exhibit a very high adhesion strength with the silicon wafer.
Specifically, even after heating for 62 hours at 120.degree. C., the
formed pattern did not peel at all off the wafer. It is considered
reasonable to understand that, even if the naphthoquinone diazide sulfonic
acid ester is crosslinked during the heat treatment, the reduction in the
flexibility of the resin layer is suppressed because the naphthoquinone
diazide sulfonic acid ester used in Examples 46 to 52 has a soft segment
such as an aliphatic hydrocarbon structure or a polysiloxane structure in
the main chain. In the case of using as a photosensitive agent a
naphthoquinone diazide sulfonic acid ester having a soft segment such as
an aliphatic hydrocarbon structure, polysiloxane structure or polysilane
structure, it is possible to achieve a particularly excellent adhesion of
the formed pattern with the silicon wafer.
Comparative Test for Evaluating Characteristics
A resin layer was formed on a silicon wafer by using the photosensitive
resin composition prepared in Example 46, followed by applying a light
exposure to the resin layer as in test 26 described above. Immediately
after the light exposure, the silicon wafer was dipped in a resist
developing solution (1.19 wt % aqueous solution of tetramethyl ammonium
hydroxide). It was possible to form a pattern. However, when the wafer was
taken out of the developing solution and, then, washed with water for 30
seconds, the remaining portion of the resin layer was dissolved, resulting
in failure to form a satisfactory pattern.
TABLE 16
__________________________________________________________________________
Examples
46 47 48 49 50 51 52
__________________________________________________________________________
Mixing of
Polyamic Acid
Tetracarboxylic
BPDA -- 17.653
-- 5.884
-- -- --
dianhydride
BTDA 19.993
12.888
17.721
18.688
11.921
15.788
22.554
(g) PMDA 4.635
-- 9.815
4.362
13.086
10.905
6.107
DPE 15.969
-- 19.219
18.819
-- 10.010
18.819
Diamine (g)
DAM -- 18.439
-- -- 19.232
8.922
--
ASi-a 1.119
0.944
-- 1.491
0.746
-- --
ASi-b -- -- 1.089
-- -- 2.178
3.267
Monoamine (g)
.ANG. -- 0.559
-- -- -- -- --
T -- -- 0.428
-- -- -- --
Dicarboxylic
.ANG.-a
-- -- -- 0.592
-- -- --
anhydride
.ANG.-b
-- -- -- -- 0.924
-- --
.ANG.-c
-- -- -- -- 0.356
--
.ANG.-d
-- -- -- -- -- -- 0.672
.ANG.-e
0.333
-- -- -- -- -- --
Synthetic
Temp. (.degree.C.)
-5.about.20
-5.about.25
-10.about.25
0.about.25
0.about.25
0.about.25
0.about.25
Conditions
Time (hour)
8 8 8 7 7 7 7
Logarithmic 0.82 0.82 0.79 0.58
0.92
0.79
0.61
Viscosity (dl/g)
Mixing Amount of
7.0 7.0 7.5 7.5 7.5 7.0 7.0
Polyamic Acid (g)
Mixing Amount of
PAC-h 3.0 -- -- -- 2.5 -- 3.0
Naphthoquinone
PAC-i -- 3.0 -- -- -- -- --
diazide compound
PAC-j -- -- 2.5 -- -- -- --
(g) PAC-k -- -- -- 2.5 -- -- --
PAC-l -- -- -- -- -- 3.0 --
__________________________________________________________________________
TABLE 17
__________________________________________________________________________
Examples
46 47 48 49 50 51 52
__________________________________________________________________________
Coated Film Thickness
4.5 4.0 5.0 5.5 4.0 3.7 5.1
(.mu.m)
Test 26 2.0 2.0 2.2 2.0 2.0 1.5 2.0
(resolution/.mu.m)
(nega-
(nega-
(nega-
(nega-
(nega-
(nega-
(nega-
tive)
tive)
tive)
tive)
tive)
tive)
tive
Test 27 0/100
0/100
0/100
0/100
0/100
0/100
0/100
(Adhesion;
Evaluation by
Checker's test)
Test 28 415 400 420 421 430 415 415
(10% weight redutcion
temperature)
__________________________________________________________________________
*Evaluation by Checker's test (Evaluation of Adhesion): Adhesion strength
with silicon wafer after heating for 62 hours under saturated steam of 2
atms.
*10% Weight Reduction Temperature (.degree.C.) (Evaluation of Heat
Resistance): TGA measurement after thermal curing at 320.degree. C.
EXAMPLES 53 TO 61
Polyamic acid solutions used in Example 53 to 61 were prepared as in
Example 30 by using the raw material compositions shown in Table 18. Table
18 also shows the logarithmic viscosity of each of the polyamic acid
solutions thus prepared. Then, photosensitive resin compositions for
Examples 53 to 61 were prepared by mixing predetermined amounts of the
polyamic acid solutions thus prepared and naphthoquinone diazide compound
as shown in Table 18.
Test 29: (Evaluation of Resolution Performance)
A layer of the photosensitive resin composition prepared in each of
Examples 53 to 61, which was formed on a silicon wafer, was subjected to
light exposure, baking treatment, and development by the method and under
the conditions as in test 17 for evaluation of the resolution performance
for Example 30 so as to form a pattern. In this test, the light exposure
amount was set at 150 mJ/cm.sup.2 (wavelength 365 nm), and the development
was performed by dipping the silicon wafer in an aqueous solution
containing 1.19% by weight of tetramethyl ammonium hydroxide, followed by
washing the wafer with water. A cross section of each of the patterns thus
formed was observed with an electron microscope so as to measure the
resolution. Table 19 shows the results.
Test 30: (Evaluation of Adhesion with Silicon Wafer)
The adhesion strength between a formed pattern and a silicon wafer was
measured by the method and under the conditions as in test 18 for
evaluating the adhesion strength for Example 30 with respect to the
photosensitive resin composition prepared in each of Examples 53 to 61.
Table 19 also shows the results.
Test 31: (Evaluation of Heat Resistance)
The heat resistance of a pattern formed on a silicon wafer was measured by
the method and under the conditions as in test 19 for evaluating the heat
resistance for Example 30 with respect to the photosensitive resin
composition prepared in each of Examples 53 to 61. Table 19 also shows the
results.
As shown in Table 19, a negative fine pattern was formed in the case of
forming a pattern by the method described above by using the
photosensitive resin deposition prepared in any of Examples 53 to 61. The
pattern thus formed exhibited a high adhesion between the formed pattern
and the substrate, and was sufficiently high in the resistance to heat.
TABLE 18
__________________________________________________________________________
Examples
53 54 55 56 57 58 59 60 61
__________________________________________________________________________
Mixing of
Polyamic Acid
Tetracarboxylic
BPDA -- 17.653
-- 5.884
-- -- -- -- --
dianhydride
BTDA 19.993
12.888
17.721
18.688
11.921
15.788
22.554
19.993
19.933
(g) PMDA 4.635
-- 9.815
4.362
13.086
10.905
6.107
4.635
4.635
DPE 15.969
-- 19.219
18.819
-- 10.010
18.819
15.996
15.996
Diamine (g)
DAM -- 18.439
-- -- 19.232
8.922
-- -- --
ASi-a 1.119
0.944
-- 1.491
0.746
-- -- 1.119
1.119
ASi-b -- -- 1.089
-- -- 2.178
3.267
-- --
Monoamine (g)
.ANG. -- 0.559
-- -- -- -- -- -- --
T -- -- 0.428
-- -- -- -- -- --
Dicarboxylic
.ANG.-a
-- -- -- 0.592
-- -- -- -- --
anhydride
.ANG.-b
-- -- -- -- 0.924
-- -- -- --
.ANG.-c
-- -- -- -- -- 0.356
-- -- --
.ANG.-d
-- -- -- -- -- -- 0.672
-- --
.ANG.-e
0.333
-- -- -- -- -- -- 0.333
0.333
Synthetic
Temp. (.degree.C.)
-5.about.20
-5.about.25
-10.about.25
0.about.25
0.about.25
0.about.25
0.about.25
-5.about.20
-5.about.20
Conditions
Time (hour)
8 8 8 7 7 7 7 8 8
Logarithmic 0.82 0.82 0.79 0.58
0.92
0.79
0.61
0.82 0.82
Viscosity (dl/g)
Mixing Amount of
7.5 7.0 7.5 7.0 8.0 7.0 7.0 7.0 8.0
Polyamic Acid (g)
Mixing Amount of
PAC-m 2.5 -- -- -- -- -- -- -- --
Naphthoquinone
PAC-n -- 3.0 -- -- -- 3.0 -- -- --
diazide compound
PAC-o -- -- 2.5 -- -- -- 3.0 -- --
(g) PAC-p -- -- -- 3.0 -- -- -- 3.0 --
PAC-q -- -- -- -- 2.0 -- -- -- 2.0
__________________________________________________________________________
TABLE 19
__________________________________________________________________________
Examples
53 54 55 56 57 58 59 60 61
__________________________________________________________________________
Coated Film Thickness
4.2 4.5 4.2 4.0 4.2 4.6 3.5 3.6 3.5
(.mu.m)
Test 29 3.5 2.0 2.2 3.0 1.5 3.5 2.0 3.5 2.0
(resolution/.mu.m)
(nega-
(posi-
(posi-
(nega-
(nega-
(posi-
(posi-
(nega-
(nega-
tive)
tive)
tive)
tive)
tive)
tive)
tive)
tive)
tive)
Test 30 0/100
0/100
0/100
0/100
0/100
0/100
0/100
0/100
0/100
(Adhesion;
Evaluation by
Checker's test)
Test 31 425 425 415 430 430 415 430 410 430
(10% weight reduction
temperaure)
__________________________________________________________________________
*Evaluation by Checker's test (Evaluation of Adhesion): Adhesion strength
with silicon wafer after heating for 62 hours under saturated steam of 2
atms.
*10% Weight Reduction Temperature (.degree.C.) (Evaluation of Heat
Resistance): TGA measurement after thermal curing at 320.degree. C.
As described above in detail, the method of the present invention for
forming a polyimide film pattern comprises a baking treatment after the
light exposure step, making it possible to form easily a pattern of a high
resolution by means of development with an alkaline developing solution.
The method of the present invention also permits readily forming a fine
polyimide film pattern having a high adhesion strength with a
semiconductor substrate and an excellent heat resistance. Naturally, the
present invention is of high industrial value.
TABLE A
______________________________________
##STR28## (QD-1)
##STR29## (QD-2)
##STR30## (QD-3)
##STR31## (QD-4)
##STR32## (QD-5)
##STR33## (QD-6)
##STR34## (QD-7)
##STR35## (QD-8)
##STR36## (QD-9)
##STR37## (QD-10)
##STR38## (QD-11)
##STR39## (QD-12)
##STR40## (QD-13)
##STR41## (QD-14)
##STR42## (QD-15)
______________________________________
In (QD1) to (QD15): -
##STR43##
- -
##STR44##
- -
##STR45##
TABLE B
__________________________________________________________________________
##STR46##
##STR47##
##STR48##
##STR49##
##STR50##
##STR51##
##STR52##
##STR53##
##STR54##
##STR55##
##STR56##
##STR57##
##STR58##
##STR59##
##STR60##
##STR61##
##STR62##
__________________________________________________________________________
In (QD16) to (QD51):
##STR63##
TABLE C
______________________________________
##STR64## (A-1)
##STR65## (A-2)
##STR66## (A-3)
##STR67## (A-4)
##STR68## (A-5)
##STR69## (A-6)
##STR70## (A-7)
##STR71## (A-8)
##STR72## (A-9)
##STR73## (A-10)
##STR74## (A-11)
##STR75## (A-12)
##STR76## (A-13)
##STR77## (A-14)
##STR78## (A-15)
##STR79## (A-16)
##STR80## (A-17)
##STR81## (A-18)
______________________________________
TABLE D
______________________________________
##STR82## (DA-1)
##STR83## (DA-2)
##STR84## (DA-3)
##STR85## (DA-4)
##STR86## (DA-5)
##STR87## (DA-6)
##STR88## (DA-7)
##STR89## (DA-8)
##STR90## (DA-9)
##STR91## (DA-10)
##STR92## (DA-11)
##STR93## (DA-12)
##STR94## (DA-13)
##STR95## (DA-14)
##STR96## (DA-15)
##STR97## (DA-16)
##STR98## (DA-17)
##STR99## (DA-18)
##STR100## (DA-19)
##STR101## (DA-20)
##STR102## (DA-21)
##STR103## (DA-22)
______________________________________
TABLE E
______________________________________
##STR104##
##STR105##
##STR106##
##STR107##
##STR108##
______________________________________
TABLE F
__________________________________________________________________________
Resin Component (Polyamic acid derivative and/or Polyamic
Photosensitive Agent
__________________________________________________________________________
Polyamic acid derivative P-1 o-naphthoquinone diazide
Polyamic acid derivative P-1 Bisazide
Mixture of Polyamic acid derivative P-1 and Polyamic acid
o-naphthoquinone diazide
Mixture of Polyamic acid derivative P-1 and with Polyamic acid derivative
P-3 o-naphthoquinone diazide
Polyamic acid derivative P-4 o-naphthoquinone diazide
__________________________________________________________________________
P-1
##STR109##
P-2
##STR110##
P-3
##STR111##
P-4
##STR112##
TABLE G
__________________________________________________________________________
<Tetracarboxylic dianhydride>
PMDA:
##STR113##
BTDA:
##STR114##
DSDA:
##STR115##
<Diamine>
ODA:
##STR116##
6FDA:
##STR117##
TSL9360 (Manufactured by Toshiba Silicon Inc.)
##STR118##
HFBAPP:
##STR119##
BAPB:
##STR120##
BAPP:
##STR121##
<Photosensitive Agent>
Same as those shown in Table A to D.
TABLE H
__________________________________________________________________________
BPDA:
3,3',4,4'-biphenyl tetracarboxylic dianhydride
BTDA:
3,3',4,4'-benzophenone tetracarboxylic dianhydride
PMDA:
pyromellitic dianhydride
DPE: 4,4'-diaminodiphenylether
DAM: 4,4'-diaminodiphenylmethane
ASi-a:
(bis (.gamma.-aminopropyl) tetramethyldisiloxane
ASi-b:
##STR122##
A: aniline
T: o-toluidine
A-a: phthalic anlydride
A-b: hexahydrophthalic anhydride
A-c: methyl nadic anhydride
A-d: 4-methylhexahydrophthalic anhydride
A-e: maleic anhydride
PAC-a:
##STR123##
PAC-b:
##STR124##
PAC-c:
##STR125##
PAC-d:
##STR126##
PAC-e:
##STR127##
PAC-f:
##STR128##
PAC-g:
##STR129##
PAC-h:
YOC.sub.2 H.sub.4OY
PAC-i:
YOC.sub.4 H.sub.8OY
PAC-j:
##STR130##
PAC-k:
##STR131##
PAC-l:
##STR132##
PAC-m
##STR133##
PAC-n
##STR134##
PAC-O
##STR135##
PAC-p
##STR136##
PAC-q
##STR137##
In (PAC-a) to (PAC-q)
X:
##STR138##
Y:
##STR139##
__________________________________________________________________________
Additional advantages and modifications will readily occur to those skilled
in the art. Therefore, the invention in its broader aspects is not limited
to the specific details, and illustrated examples shown and described
herein. Accordingly, various modifications may be made without departing
from the spirit or scope of the general inventive concept as defined by
the appended claims and their equivalents.
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